I disagree it was all just for show or all Xena. Gabrielle accepts her responsibility as queen to lead regardless of her vow of pacificism and grief about Ephiny. Everybody knows Xena's the real battle strategist, but her "isn't that right, Gabrielle" deference communicates she is still second in command to and derives her authority as a non-Amazon from Gabs. As Xena tells Amarice, she gives and demands respect for Gabs, no matter how much she may want to throw Gabs' peacenik ways against a tree. She's also letting Gabs know she has her back and won't take orders from anyone else. For her part, Gabs has the courage to resist everyone else's instincts for vengeance.

I believe Xena would've let Brutus die from the pinch, had Gabrielle not stopped her and ended up enabling more choices with him alive. Xena orders the "Pompey Q," she knows Gabs wouldn't like but the Amazons are revved for, just as they were for killing Brutus. Once Xena realizes she's got the Brutus option, she frees the Romans from their roasting spits, pointedly telling the Amazons they don't kill unnecessarily in Gabrielle's tribe.

The beauty of their relationship to me is that it's not focused on hierarchy or posturing for others' benefit. They try to work through their different approaches and give each other the benefit of the doubt, usually resulting in a better solution than each simply going her own way. In this case, it was a combination of Gabs' sparing Brutus and Xena knowing how to use that to their advantage.