A little similar to a previous prompt, but specifically set after Endgame where Steve travels back in time and chooses an alternate reality where he's friends with Howard and sees Tony grow up. Steve acts as a sort of parental figure to young Tony due to Howard being absent/alcoholic. Steve doesn't tell Tony he's from a different reality until they start a relationship (no underage, happens after Tony becomes Iron Man) but has this internal conflict where he struggles with keeping it a secret until he thinks Tony is ready. Civil war is avoided because they talk through their issues, and they might have a few kids down the line, but ultimately they end up happily living out their lives together in this new reality.

Can be any rating from G to E.