Credit goes TheSheepl

Mars usually overprotective of his older sister, Venus due to her being the second rarest breed of Lugia (first being his adopted mother, Veronica). He was annoyed when a Grumpig was constantly hitting on her. He checked out his posters to see that the Grumpig is wanted for capturing pig pokemon and selling them to farms at a high price, which angered him more that a criminal was trying to flirt with her.
When he heard that he planned to capture her, he sprung into action. The grumpig saw the infamous red bird and begged to let him go, but Mars wanted none of it as he gave the Grumpig a full blast of his Pamp Breathe.

Venus happy that Mars looking out for her, but she can take care of herself, which Mars was ok with. As for the Grumpig, Mars wasted no time taping him up around his waist and was gonna taunt the pig on their way to pamper down, hopefully the staff can find the lost pig pokemon he sold.

End

Despite Mars' hardened personality, he cares deeply for his siblings given they were all separated, Mercury he not that concerned with, but can be a little protective of Venus given she's always being hit on and usually the second to be hunted the most.

Mars belongs to Me
Pokemon belong to Game Freak