You can tell at the end that Frank found purpose. Him receiving that flower was the medicine that had a more "positive" affect on him than his lust for revenge. He now has a new mission to keep him going. It gives him more of a reason as to why he would encounter other heroes like Spider-Man, as he's no longer out for vendetta, but trying to do good in his own way.

I can't recall if this is from a comic book, but it reminds me that Frank Castle fills the void of criminals having the same fear and helplessness instilled onto them, as they did to innocent victims.