My head canon if bruce found out Bart was lying bout the future
" Worlds so called greatest detective takes this long to bring together proof I've been lying. " Bart slow clapped mockingly at the Dark Knight. The Team had been curious, and suspicious when after a mission the protector of Gotham pulled Bart aside bitterly. Bart didn't so much as bat an eyelash. Batman accused the new Kid Flash about lying, deceitful and manipulations for the past few weeks. Accusing Bart of persuading became vigilantes and risk their lives, and had a photograph of Bart talking with a known wanted killer.
" In my time we couldn't believe that a man without powers could fight gods among men and always overcame his inner darkness. How he gathered a family and by day pretended to be Bruce Wayne playboy jackass. But if your wondering why I decided to stay here for the rest of my life and change things you have to understand Barry, the team, and the League would've died or been forced to suffer without my help. I've been here trying to save as many of you as I can. I stopped my best buddy from being under the Reach's control. If I hadn't humanity would've be enslaved. "Bart revealed part of his torso and his arms showing scar tissue." I grew up starving and mostly alone. Wally would've lived barely a year after Barry's death. Becoming obsessive and creating this formula to make him faster and injected it into his veins. Died from a overdose after snapping and Artemis killed herself."
" Your eldest would've died killed by another one of your children. Tim would've become a brain washed killer that served the Reach for a decade before someone took him down. Babs crippled then tossed aside like trash helping people before she was gutted. But sorry for this a little spoiler. You knocked up an Assassin and have a bastard demon Brat. You got a week before she arranges a meeting and drops him off with you. Oh and Jason got brought back to life and he's currently killing scum bags and is the new Red Hood. Oh and those people I encouraged are going to be joining you. Stephanie, Carrie, and Duke are perfect Robins from what I think well they won't be boy or girl wonders but be Spoiler, Catgirl and Signal. I saved the world and I lied a bit and gave you helpful info. So am I the bad guy?" He asked sarcastically before running away with a big smile.