Jason Aaron and Simone Bianchi close the origin of Thanos out in "Thanos Rising" #5. While I can appreciate that Aaron has tried to make Thanos a sympathetic character, it's a tough sell. Death's flirtations with Thanos (young or otherwise) throughout this series adds some dimension to the relationship, but does little to amplify Thanos' street cred, as it were.
For all the passion Aaron tries to imbue on Thanos, I've always preferred the Mad Titan to simply be mad and power hungry. I don't need to know that he flayed his mother alive or killed a group of classmates in an iguana-filled cave. I simply need to know that Thanos is evil. Aaron gives more than enough of that in "Thanos Rising" #5 to wash away the first four issues, although those were constructed to be the foundation for Thanos' ascent. There are a few eyebrow-raising moments in this issue and there is a story yet to be told beyond this issue, but I am enjoying Thanos in "Infinity" much more than I do here. The present day version is desperate and advantageous, scheming and determined. Aaron could undoubtedly have a field day with those characteristics.
Aaron doesn't get much support from the art. Bianchi's art is a little too flowery for the death and destruction unleashed by Thanos, and much of the carnage just melts together under detail. It makes for some pretty images, but doesn't fully convey the magnitude of evil unleashed upon the universe in "Thanos Rising" #5. The emotional bits flourish under Bianchi's art, but the harsh reality that Thanos levels on Titan is too ornate to be brutal. Bianchi's style reduces the cosmic nature of this adventure to a set piece that is drained of emotion and becomes almost clinical.
A five-part miniseries to tell readers, "Thanos is a lonely bastard" seems a bit severe and a little to close to the failed model executed through the "Star Wars" prequels. I'm not sure what benefit Thanos' legend gained from the grade-school adventures of the mad Titan, but this issue, like "Revenge of the Sith" does a decent job of elevating the evil titular character to expected levels that should have been present earlier. Mind you, Jason Aaron hasn't failed in delivering a compelling story, but Thanos is compelling enough without any backstory -- especially backstory that isn't particularly electrifying. I'd like to see Aaron handle the Mad Titan again, but with a more animated artist and in a more cosmic setting.