We get closer to the heart of why Zed seems to be a bit hostile to his half siblings.
Block, thus far, has been the only one to really confront him about these issues.
Zed means no real harm, but it's all still a sore subject after a rough childhood.
We'll get to the issues with Zed's mom and step-dad at a later date.
Also, for those wondering, Block is invulnerable.
That's his entire powerset. Super-toughness, reduced pain reception and a low-level control of his own density. Truthfully, as far as invulnerability goes, he's even more solid than Zed is.
Those gunshots actually sting Zed like crazy, even though he deliberately tries to never to show that sort of thing to his enemies.
Block isn't feeling a thing other than annoyance that rude-ass bank robbers are shooting at him while he's talking.