I have no idea if this is already a thing, but consider: An MMORPG with an in-built buddy system. Like you can simply become allies with another player, but there's a levelling system in it, where both players get XP and other benefits the more they work on it together, do quests with eachother and other kind of tasks.
Every character you make gets randomly assigned a favourite thing (or you get to pick from a few options, but some in-game system ensures that none of the options are more common or rare than any other), and that thing is a quest item. Like a favourite flower, a rock, or some specific bird's feather. You gain barely nothing from obtaining it yourself. A thing that's not your favourite but someone else's is useless to you. But giving it as a gift to someone whose favourite it is has huge perks to you both. That is their point and goal. They are meant to be given as gifts.
Your healing factor and recovery speed go up when you're within range with a friend. Some in-game quests and challenges are essentially impossible by yourself, or with an allied player who's only an aquaintance, but can be managed with a close friend. If you manage to max out friendships with five other players, all five of you are essentially invulnerable when teamed up to play together. You'd have to be an idiot to manage to get yourself killed in such an arrangement.
Which unfortunately is still entirely possible, since all five of you only share one braincell when hanging out.
