User blog comment:IamJakuhoRaikoben/Chapter 443: And Then, The Land Was No More, Review./@comment-7418318-20150706191908/@comment-24102956-20150707004044

Brandish just wanted to "even" out between them when Natsu stupidity goaded her to fight him after Marin severely injured Mestbolt even if Team Natsu were shocked and horrified that some weird dude who is all nice to women and axe-crazy on men was killed.

I bet they're upset that they couldn't get revenge on Marin after he easily played around with them. It happens all time when bad guys beats them first then Team Natsu taunts them to fight them for a second round where their Nakama Magic wins the day.

I believe Makarov became a political hostage as a condition of the treaty with God Serena as a member of the Spriggan Twelve to appease the Albareth Empire. That's how politics work.

As for Brandish's dislike for war, I think she just wanted some star mango shakes for some relaxation and was being nice to FT before being pissed off by Marin.

And about Marin, I think he's trying to hit on her and she finds it disgusting. Thanks to Natsu's stupid mouth, it gave Brandish an opening to finally get rid of him permanently.