If ever there was a family that needs some SERIOUS therapy, it’s the three sons of Steffon and Cassandra Baratheon: Robert, Stannis and Renly.
We cannot discount the destructive influence on the elder two of witnessing their parents die at sea in a storm. They literally stood on the ramparts of Storm’s End, hoping to see Mum and Dad come home…. only to see Mum and Dad’s ship be broken apart, knowing everyone on board would drown in the raging seas. (Except Patchface. Why Stannis kept him around is perplexing – the ultimate masochistic reminder of his parents’ fate?!)
Renly escapes this trauma, only to have his own trauma of growing up raised by his brothers (one literally distant and the other emotionally distant) and his castellan.
Nearly all the problems engulfing Westeros right now following the War of the Five Kings, not to mention that actual war itself, could have been avoided had these three brothers been able to actually talk to each other…. y’know, with words and stuff.
House words in Westeros aren’t just a catchy buzzword. They’re a mantra, an ethos to the way that this family works. Even after she’s Lady Stark, Catelyn Tully Stark makes decisions based on the Tully creed family, duty, honour. Daenerys spends her arc from Pentos to Meereen to the Dothraki Sea again figuring out what it means to bring fire and blood.
So if the Tyrells want to grow strong, work their way up the social chain, into positions of power, and have a Tyrell child one day be King on the Iron Throne… why marry the gay Baratheon brother?
This post could also be titled: the Tyrells knew all about the Lannister twins incest, because Mace’s enthusiasm for a Tyrell King only makes sense if he knew that a child born to Renly Baratheon had the best chance of ending up on the Iron Throne.