Curate, connect, and discover
Jason obviously has things he's ashamed of, even though he's this ass-kicking God we all love, he still has his demons. One of those demons being certain scars. Ever Hero, vigilante, and Villain has those certain scars that they don't want people to see or know of. For Jason, it's the ones from the Laz pit and when he died. He hates them, wishes he could get rid of them, but they're a part of him.
Bart has scars of his own, one's he wishes to never show. That being, all of them. He shows people his outter shell, this fun, party loving speedster that's always quick with a joke. In reality he hides most his pain behind that mask because no one expects the outgoing one to be the most damaged, but that's just what he is. Damaged. So damaged he fears peoples reactions to his real self and became his character "impulse". The scars from the future, from being enslaved and tortured, from fighting back and losing so much. He hardly looks at himself because of them. He may be quick to heal but the scars run deep.
Jason and Bart find a mutual understanding in not wanting to share the scars stories and be complacent in showing them, but not showing off. It's better that way.
Okay, so let me get this all straight for those of you who don't know comic Bart or at all: Bart Allen's dad was gone and his mom couldn't take care of him constantly being on the run, so he was basically a lab rat for a scientific facility since... b i r t h just about. He was put into VR as a sort of sedative and to keep up with his vastily progressive mind and body since he aged about 200x the average person. (By the time he was three he looked 13) But in a way, speedsters have this kinda "dog years" effect in that everything in the world for them is slowed because that's just the way they see everything. So, in technicallity, while the scientists only had him for three or four years, to Bart it was 16??? And don't get me stArTed on the physical and pshycological effect of that. He never saw another living person until he was 16. He never had any kind of physical contact until he was 16. Could you even imagine?? No wonder the kid is so touch starved. (I feel like him and Kon bond over the fact they're younger than their bodies progression but besides the point). So he's been in this facility for 16 years, spends all that time in a Virtual false reality where his only friend was some weird VR program named Dox, which is probably symbolysim for the doctors that experimented on him when he was put under, and which he named his dog after, he's never felt affection or talked to people outside of that, never got a chance to meet his parents, has more villain relatives then Hero and STILL didn't go to the dark side after THAT?? Can still show off the best fake smiles and persona front after all that?? Had to endure more than MOST EVERYONE in only THREE YEARS which was actually SIXTEEN and STILL is GOOD?? You cannot tell me that this is the bravest kid you've ever read about, you cannot. And even with all that, he finds it in himself to forgive many of those who've wronged him. Listen, Bart Allen is by far the most amazing character I know and you can fight me on this. He's been through more than all the Batfam COMBINED. If he wasn't so bright and cheery, I bet Bruce would've adopted him. (another thing I forgot to mention, the fact Wally practically gave Bart away to Max and made the kid feel unwanted, even though Max became like the only crutch Bart had/a father figure, not even Barry wanted him when he returned from the dead. Assholes) He's died FIVE TIMES and he's still a hero. He's experienced this over and over, and still is a hero. He left his home and practically erased it's existence so now he's a time anomaly, who doesn't really fit in anywhere in time, and is still a hero. Fuck your favourite angst characters, Bart Allen takes all the cake.