Okay but like in your opinion what is the most likely scenario of Scaramouche like, redeeming himself or at least making traveler not hate him so much so that he could be playable? (Sorry if that doesn't really make sense I have no idea how to explain my question ;-;)
No, the question is totally understandable:)
I think the traveller rather hates the concept of the fatui and not necessarily its harbingers, if that makes sense. Everyone has their own motivations to be in the fatui and the Balladeer's one has nothing to do with the actual plans of the Tsaritsa. Let us not forget that he's also going to betray her! You know the saying: my enemy's enemy is my friend. Therefore I think he's still very much redeemable in our eyes.
The only thing that makes it a little complicated that he indirectly caused Teppei's death. But then also, the traveller has a big heart and if he learns about his story, I think he will be capable of forgiving him. (Potentially happening in the Yae Miko story quest? Since she's met and knows well what happened.) So I think, when Scaramouche gets in trouble for stealing the gnosis and the whole of fatui will be after him, we will (maybe? maybe) help him. Especially since he's gonna realise that putting the gnosis in wasn't actually worth it. Then he'll have the full chance to join the traveller's party. Just imagine: he can't go back to Inazuma and now has to hide from a literal army and eleven blood-thirsty harbingers as well, where else could he possibly go?
My only fear is that his redemption arc will also contain him dying. We can't possibly know if putting the gnosis in isn't dangerous even for him. Also, this last sentence of the artifact set makes me really anxious:
"But if he were to wrench this "heart" out,
He would no longer be able to feel anything at all..."
WHAT THE HELL IS THIS SUPPOSED TO MEAN. Does not feeling anything means death? If someone gets the gnosis out of him, will he die? We do know that the Tsaritsa really needs the gnosis, will she try to actually like rip it out of him...?
So to sum it up, I think he's very likely gonna have a redemption arc (and then hopefully become playable.) But his chances of dying are also worryingly high...