Paps cuts, revealed by Undyne, he's suicidal because we keep secrets from him, that people think of him as just a kid... How everything is a lie to him and how he should die.
Thats what its been the past 10 years. Through this as time passed he 'died'.During his death he brought their mother, Ariel, back from the dead and had gain a personality disorder from Core Frisk, starting AU Rumble.
He meets every other Papyrus that are being controlled, to make everyones memories re appear he has to defeat them all, the more he defeats, they come back to life, and join Papyrus. After the shenanigan Ink warns Papyrus about future villains, so there starts the AU Patrol.
He has 2 sons, one was from his ex-husband Mettaton, who's name was Impact, and the other is Fell, with a son named Nem.He's a master of many weapons, he has the powers to make a shield, to make blasters and has two forms.
An angel form deeming that he's a pure heart, wanting nothing but peace in the multiverse, he also has the ability to turn purification, where he uses the powers of every Papyrus combined into one form. This makes him the strongest in the multiverse.
He also has some mind powers, such as being able to talk through people trough their minds. He's a well known fighter and should not be underestimated.
Don't think of him as the Undertale Papyrus everyone knows. Cause he's not the person you seem. He isn't a goofball. In the end he has the toughest past, even more then Sans. Though through his experiences it appears to be useful when fighting threats.