When Barry first saw his mother again in the Flashpoint universe.
Barry's Mom: It is okay for a busy young man to forget his old mom.
Barry: I could never forget you.
Flashpoint Superman, despite having every reason not too, shows up near the end of the film to save Cyborg, the first friend he's had in his entire life.
Turns into a Tear Jerker when Vic dies moments later anyway.
Doctor Vulko, the one Atlantean who felt guilty about what his people were doing and freed Captain Atom simply because it was the right thing to do.
The best example is at the end of the film, when Flash gives his Batman a letter written by his father from the flashpoint universe. Bruce, who instantly recognizes the handwriting as his father's, breaks into tears and thanks Flash.
Batman: You're one hell of a messenger. Thank you.
When Flash reveals to FP!Batman that his son is Barry's version of the hero, it's heavily impled he figured out he dies in Flash's timeline. Does that stop him from helping Flash? Hell no.
FP! Batman: If I were to help you, what exactly would we need?