The grudge isn't for fighting back in battle. The grudge is for killing his brother. Yes, Loras and Garlan understand war. Yes, Garlan is reasonably mature and level headed. It's still his brother.
I'm not exactly arguing that he should be pal'ing around with Horpe and Stannis. I'm saying that he's acting very strangely. In a way that makes little sense.
Let's take a look at his behaviour prior to when Alester starts talking shit:
Chapter 26: Bitterbridge
"I thank Ser Garlan," said the Tully born matron as she nodded to the young Tyrell knight "I thank you, and offer my condolences. I was not personally a witness to your good brother's passing, but he led Lord Renly's van bravely and fought fiercely at the front. I-"
"Who killed him, my lady?"
At that Catelyn Tully hesitated.
"Ser-"
"Please, my lady. I would know."
Nothing to take issue with so far. His brother and Renly were killed, and he wants to know by who.
"Your brother was very brave, Ser. He cut down half a dozen knights I am told, fierce fighters all. Knights hailing from House Follard, House Penny, House Scales, House Suggs, House Whitewater, even the lord of House Sweet-"
"My lady," said Garlan again, his voice a little colder "I would have answer."
"... Ser Richard Horpe was the man, I was told. He fought him when both were afoot and cut him down amidst the entrenchments. Him and Renly as well, when Renly waded into the melee himself after Ser Loras's death reached him."
At that murmurs broke out amongst those assembled, as Mace Tyrell drew inward to himself and Garlan Tyrell's lips tightened into a frown.
"And how did the Lord Stannis honour him for these daring feats? A promise of a lordship? A highborn bride? Truly, I am curious. What was the giftgiven for my brother's life?"
Garlan starts talking shit about Horpe, in the strangest way possible. I assume from the antagonistc context and word choice that 'daring feats' is supposed to be in a vaguely sarcastic tone, though I can't rightly understand why. Loras was a decent swordsman, and both he and Renly were armed and armoured. It might not have been as impressive as perhaps cutting down the Mountain would be, but it's still not exactly something to sneer at.
And demanding what rewards his brother's killer was supposedly given came a little out of left field. Is it universal to give out tangible rewards to everyone who killed someone of note, to the extent that it's expected? If so, why's Garlan getting up in Catelyn's face about it over an established custom? If not, why's he flinging shit at the opposing side for doing better than the men of his own army?
There's nothing technically super-illogical about this, granted. I don't have a problem with Garlan grieving for family, or not being on great terms with the people who killed them. But the way it's executed seems forced, making it seem much more like Garlan's having a go at Catelyn because Droman needs this scene to end in conflict and tension for plot reasons.
Again Catelyn Tully hesitated, but answered without a second prompting.
"He has given him nothing yet, Ser Garlan. His Grace has indicated that all accounts and matters will be resolved when the war is ended. Ser Richard has chosen to abide by that."
At that more murmurs broke out, and Garlan Tyrell could see the greedy looks on the faces of the Florents, the looks of concerns among those Stormlanders who had declared for Renly first.
"Nothing," murmured Garlan nothing, as a bitter laugh escaped him "He gave him nothing."
Garlan is apparently aggrieved his brother's and brother-in-law's killer didn't get shinies for it. Seriously, whose side is he on?
"Ser-"
"No, my lady Catelyn!" said the Tyrell knight with a wave of his hand to cut her off "You have said it clearly, and I would make those present understand it. Ser Richard Horpe, a knight of Lord Stannis Baratheon. A man who can be named his champion, if the Lady Stark's words are true. A man who felled my brother, a man who felled Stannis's own brother! And what reward has he received for his great efforts? A highborn bride, and perhaps a lordship as well? Brienne of Tarth went east with Renly, did she not? A fitting bride for a loyal man. But we do not hear such from the lady, do we? We hear nothing at all, nothing but promises that accounts will be settled, that problems will be resolved."
As above. Go ahead and tell me this is how people react when their family members get killed.
Personally, I don't think Garlan would be spoiling for a fight at this meeting. But that's just my interpretation, and if he was, but behaved in a more realistic manner, I'd accept it. As it is, this stands out to me as poorly written.
He let his words linger in the air, a silence following in their wake until he chose to continue.
"Tell me, you knights and lords of the realm. Does that seem a lord to follow? A king to serve? One who does not even reward his most leal servants? How will you then fare, you who raised your banners against him? Do you think he will forget your actions? Do you think he will let you slink away to your homes, as some have already done? That you can but hide in your holdfasts, and pretend all will be forgiven?"
Garlan's apparently going to satisfy himself with trying to poison the well of Stannis' supporters over how Stannis didn't immediately descend on Horpe and shower him with rubies and brides. How petty.
Nothing illogical about pettiness, either, but it still.
When Robb's brothers died, he fucked his life and kindgom away.
Ignoring that it isn't at all equivalent to compare Robb's younger brothers who were captured and murdered (as far as he knows, anyway) outside of battle by a man he considered a brother, to Garlan's family that picked a fair fight and lost it, I'm not suggesting that Garlan not be in mourning. Or be emotional rather than logical. Or even be on the verge of pissing away any chance of a peaceful alliance with Stannis (though this last one I wouldn't
expect of him from what we know of him in canon).
I'm calling out a scene that makes little sense as written, that's all.
I've never noticed that. Sure, some of the Florents are scum, but I haven't seen enough of the family to damn them as a whole. Most families have some scum here and there. Calling them incompetent and unlikable as a whole is a bit of a stretch.
Le shrug. I have. I can't quite recall anything in the way of a redeeming qualities from Martin's portrayal of them.
For Christ's sake, he even hammers it home via the Halo Effect by making them look ugly/physically unattractive, what with their distinctive 'large ears'.