Family Problem

He’s got to start crafting his own persona at some point. Perhaps consider getting him some store credit if you have the means to help him get started. And maybe help him pick a good username.

Why not family-share your Steam account with your nephew? I honestly don't quite see the problem here...

Okay, your post is a bit unclear, so I'll approach it from two different interpretations:

If your nephew simply made a broad inquiry into whether sharing was possible, without being aware of the technical elements involved:

I can think of a method that'd allow for Steam account sharing [origin and uplay are probably lost 'causes, and I'm going to just assume you were kidding when you indicated caring whether or not you lose your epic account (:P) ], but it strikes me as being really too much of a hassle to bother with. By that point, you're probably just better off dropping the accounts, than trying to figure any workarounds out, if you're already feeling some inclination of dropping them to begin with. Nevertheless, having him get his own accounts and simply borrowing yours until he works his way through your current games is likely still a superior option if you don't have any special consideration toward yielding the accounts.

Of course, if your intention is to gift him a bunch of games as a sort of celebration gift of his first PC, in that case you can just think of it as a gift of games, rather than considering it as losing your collections. If you don't have any online-stored save data that you can't bear to lose, then there's really no harm in giving them the accounts. It's easy enough to rebuild game collections later on, if you get more interested in gaming again.

Flip side, he's 12. Regardless of how much he's been playing, unless he's a gaming prodigy or has been playing microtransaction games or similar, then it's extremely likely there's actually anything that he'd really hurt to lose. For things like online shooters, which seem to be the main focus, there's usually not much to lose by starting over to begin with; Unlocks can be reobtained, and skill ranking reearned. So there's not much 'cause to yield the accounts over if you don't have an inclination to do so.

If your nephew outright asked for your accounts:

If you teach him that he'll get rewarded for acting entitled, you'll risk utterly ruining him as a human being. With that as the alternative, there's basically nothing that'll justify giving him the accounts.

It'd have been a completely different thing if you'd offered it, but if he's asking for it, that means he already doesn't respect your considerations. Moreover, it also indicates that he either has a social perception issue or has already begun to develop an inflated sense of self-interest. At 12 years old, that's rather problematic behavior, regardless of the basis.

he should start all over . maybe give him some store credit to help him. so that he learns to value his stuff.

Sharing should be fine but either way this is a discussion you should take with him. If he continues on a shared or gifted account, he might regret it later and have to deal with the consequences because it'll always be harder to start over the longer you've already been committed. That's why you should avoid sharing and have separate accounts from the beginning if you plan on any long-term usage. Most people prefer to keep their progress on personal accounts so unless he already knows that he'll never care about it, starting over now is better. I don't know about the particular games you mention but it should be possible to transfer some of his progress if the items are tradeable for instance.

Fortnite is free so you should've made him his own account to begin with if he played it so often. I'd also agree with helping him start over if you can spare the money, build up his own accounts and set of online games slowly so he learns various values of having his own stuff. Life skills and lessons, and I'm sure he would appreciate being the one to make his own account from scratch in the future. He may be disappointed now but the accounts were not his to begin with, even if he "worked" on them more than you.

Sooth made all the points I was thinking about too, unlocks can be re-obtained, some items transferable.

Share the accounts but make him new ones for the new games he will be getting. Eventually those multiplayer games will die out, or he'll be bored with them and you'll have exclusive access to your accounts again :p

Like someone else mentioned above, you should have given him his own Fortnite account, the game is free!
I can understand his frustration now, but life sucks and you don't always (almost never, let's be real here) get what you want or what you think you deserve, he will just have to start over, explain him why and if he gets mad about that, than that's his problem and not yours, he should appreciate you even let him play on your computer and accounts in the first place, sure he may be only 12 years old, but they are your accounts!

Help him with making his own accounts - He should be making his own choices in gaming. I played on my dad's accounts when I was young for online paid games, then I made my own steam account when I needed steam to play CS:S. He is 12. Not 5. I was creating my own accounts for games younger than that.

Once he has his own accounts, he then has the freedom to do what he wants with those accounts.

Online games are easy to grind if you have time. I wouldn't mind giving him the logins for those. But if we're talking about steam account that's a different story.

Give origin, uplay and (especially) epic to him. Leave steam for yourself. If you'll ever want to play something that was on those other accounts - well, you'll have to buy it again. But how much could it be?

Nah, I wouldn't share anything. Fact is that those accounts are yours and the kid's old enough to realize that. When breaking the news, feel free to sympathize with him a bit, but make sure he understands why you aren't giving him your account.

Offer to help him set up his own accounts. If you want to be a top tier uncle, then get him something to start him off. Some V-Bucks to kick off his Epic account and maybe the Season Pass (I think they're doing those) and a couple of fun games on Steam.

Setting aside the issue of his motives, as well as the issue of the value of those accounts, for me the answer is still a strong: "Sorry, but it's not possible. It would be against the rules, and it would practically require me to stop using those accounts myself." Depending on his perceived motives, and on the way this request has been presented, and your refusal will be taken, I would decide, how much I want to help him in establishing his own accounts.

What you have been doing so far, seems to be within "family sharing" rules. What he asks for, would make you strongly break the rules. In case of a 12 y.o. this could set for him a very bad example, indeed becoming a starting point of future corruption.

It's not, that I'm 100% Lawful Good in my RL, actually I'm like 90% Chaotic Good. Sharing the account would be off limits for me, but gifting could become a choice under some circumstances, because I do not agree with the rules forbidding us from changing ownership of stuff, that we have acquired (it is a form of extortion for me, when we are practically forced to accept such rules). However, I strongly believe, that in a case of 12 y.o. (and especially, taking into the a consideration, that it's a 2k game account, which for him probably means "riches beyond imagination") it's too early for introducing him to such nuances.

Saying this, I would probably try to get those account transferred to his account by the particular games' support, but only after dealing with the issue of sharing. Especially, if it was only him playing those games, and there was only 1 active account created, there it seems at least worth a try.

We need to learn frustration. This is a part of becoming an adult I think. :)

FIRSTLY: He's your nephew, NOT your son - be careful not to usurp his parents responsibilities in raising him. Also make sure he realises that gaming is a privilege, and not a right.

I also have a nephew who recently got his own computer (turned 13 a few months back). I recommend setting him up with a new Steam account, and start offloading your bundle extras onto that account. I have a second Steam account. I added family restrictions to the account so that he just has access to games, and not to the steam community, store, etc - mainly cos of the huge influx of inappropriate game content on Steam nowadays that can still be visible at times - and also because I'm not his legal guardian and he doesn't live with me, this puts a reasonable safeguard in place that I can't actively monitor without. Obviously if he's playing multiplayer games this can make it tricky at times, but in general gameplay it is fine.

Outside of Steam, places like Uplay, Origin, etc have a clean storefront, so the social and visual interactions are less worrisome.

I'm really impressed and happy with how this conversation went on. Mature and constructive and understanding, unlike a co-worker who told me to grow up and leave the game to the kid. Thanks a lot guys. You are great and really helpful.

Letting him play on your accounts instead of having him make his own for free games was a mistake.

Anyway I think you shouldn't give him your accounts, nor share with him (except for steam family sharing I guess). He has his own PC now, he should start over. He is only 12, he has all the time he needs to grind stuff again in those free games.

Also he shouldn't feel entitled to your accounts just because he played on them, instead he should be grateful he was allowed to use them in the first place.

I would just give him my accounts and would start over myself :)

As other people already said - at one point he will have to make his own account.
As he gets older this sharing will be more awkward and troublesome - especially since many people use steam as sort of social platform.

It may look like end of the world now, but honestly he will probably get over it faster than you think. Its possible that he will change games completely in year or two. Sooner you do it, less painful it will be.

If you really want to be "a father figure" than give him nice lesson about standing on your own feet and sweeten it up with pros like picking own nickname, avatars, being independent and making friends. ;p

He needs to start all over on his own. He needs to understand that this is how it works.

Since he is only 12, he can start over.

well, since you already put it as an option, i'd say give him all your accounts except for steam.