How much loyalty or influence does Mace Tyrell hold over his vassal lords?

[Syl of Syl]

Seems like both not much and plenty at the same time.

The Hightower clan have been doing their own thing the whole series as they apparently have done for most of the history of the Reach, so I don't think Mace has a lot of direct authority over his most powerful vassal. In name he's the Lord Paramount of the Reach, but I think the Hightowers and the Redwynes are at least as powerful. Paxter Redwyne is both Mace's cousin and his goodbrother but if not for those close family ties, Redwyne could easily go their own way without any serious consequences.

I think if you want to know how strong Mace's hold on the Reach is and speculate about an uprising we need to talk about House Florent though. They are already in defiance of Tyrell by joining Stannis. And now Alekyne has arrived in Oldtown hoping to get help to take their seat, Brightwater Keep back from Garlan. If the Hightowers are going to do something here, there is a chance they undermine Mace and the Tyrells by aiding Alekyne Florent in retaking Brightwater. Alekyne has sisters married to Leyton Hightower and Randyll Tarly so he's not without influence in the area. And House Tyrell making a power grab in Oldtown's backyard has to be concerning to somebody in the Hightower clan.

All that said, the Tyrells have done a good job tying the two most powerful houses in the Reach to them with marriages. Lady Olenna is Paxter Redwyne's aunt as well as the grandmother to his children through Mina Tyrell. They are basically one big happy family. And Mace Tyrell is married to Leyton Hightower's daughter, making their children (including Garlan, the guy who took Brightwater from Alekyne) Leyton's grandchildren. So until there are some deaths to some of the older people in this power structure, I don't think we're going to see much outright defiance of Tyrell power.

[Karneol]

I reread a certain chapter for another topic and in the end its claerly said that Mace shouldnt trust his bannerman

It chapter with the dialog pf Cersei and Kevan. When it comes to possible small council canidates Kevan said this:

Quote

"Mathis Rowan is sensible, prudent, well liked," her uncle went on, oblivious. "Randyll Tarly is the finest soldier in the realm. A poor Hand for peacetime, but with Tywin dead there's no better man to finish this war. Lord Tyrell cannot take offense if you choose one of his own bannermen as Hand. Both Tarly and Rowan are able men . . . and loyal. Name either one, and you make him yours. You strengthen yourself and weaken Highgarden, yet Mace will likely thank you for it." He gave a shrug. "That is my counsel, take it or no. You may make Moon Boy your Hand for all I care. My brother is dead, woman. I am going to take him home."

What do you think? Is Kevan right?

[Syl of Syl]

Mace does seem a bit of a fool. Even his mother doesn't have a high opinion of him. But I don't think Kevan is exactly saying that Mace can't trust his bannermen there. He specifically calls them loyal men. He is not suggesting having them turn on Mace but rather taking them for her own so that Mace has one less loyal, able bannerman. So yes, Kevan is right. That is a smart play, but not something that would directly lead to an uprising amongst the Reach lords.