this isnt allowed, Marval characters do not originate in games, especially Thanos
However Kain would win easily, his too big, Kain is so fast he could easily dodge Thanos blows at the same time as teleporting and then stab him in the skull with the reaver, draining his soul and killing him. No matter how large or powerful, when its got a soul, the reaver takes his life away.
dang..that's right...i'm used to posting in the comics forum...i forgot I was in a different forum for a minute. Thanos is banned from Death though...Death will not have him...so, Kain could not possess his soul. I don't think Kain has fought anything on the level of Thanos though...especially a Thanos with the IG or HOTU
i agree, both indestructable, but without a soul how can Thanos live? and death doesnt recieve the soul, Raziel eats it, TBH if Raziel swallowed a soul from someone as powerful as Thanos Kain would become many times more powerful than a God, since he is basically already one but i dont see either really winning unless taking Thanos soul works