Background

In this post I thought it would be fun to explore just who could wear Alayne/Sansa's favor in the upcoming Tourney of the Brotherhood of the Winged Knights. At the end of her first TWoW chapter, she tells her potential betrothed (Harry the Heir):

He grinned. “I will hold you to that promise, my lady. Until that day, may I wear your favor in the tourney?”

“You may not. It is promised to… another.” She was not sure who as yet, but she knew she would find someone.-TWOW, Alayne I

and I thought it would be fun to look into some of the potential candidates for "Another".

If interested (I tried gathering all the info on the Tourney in general in one place): The Tourney of the Brotherhood of the Winged Knights

"Another"

Ser Lothor Brune aka the Appleeater

The most likely answer, as not only is he one of the heroes of the Blackwater, where he earned the name Apple-Eater for his feats against the Fossoways:

the freerider Lothor Brune, who'd cut his way through half a hundred Fossoway men-at-arms to capture Ser Jon of the green apple and kill Ser Bryan and Ser Edwyd of the red, thereby winning himself the name Lothor Apple-Eater

If interested: Most Impressive Feat in Battle

but he has also protected Sansa before from Marillion:

Sansa heard the soft sound of steel on leather. “Singer,” a rough voice said, “best go, if you want to sing again.” The light was dim, but she saw a faint glimmer of a blade.

The singer saw it too. “Find your own wench—” The knife flashed, and he cried out. “You cut me!”

“I’ll do worse, if you don’t go.”

And quick as that, Marillion was gone. The other remained, looming over Sansa in the darkness. “Lord Petyr said watch out for you.” It was Lothor Brune’s voice, she realized. Not the Hound’s, no, how could it be? Of course it had to be Lothor …-ASOS, Sansa VI

and we already know his opinion of Harry (if interested: "Ser" Harry the Heir and the Tourney of the Brotherhood of the Winged Knights):

Near the keep, she ran headlong into Ser Lothor Brune and almost knocked him off his feet. “Harry the Heir? Harry the Arse, I say. He’s just some upjumped squire.”

Alayne was so grateful that she hugged him. “Thank you. -TWOW, Alayne I

and:

“Well, I’m not. He may think he’s some great knight, but Ser Lothor says he’s just some upjumped squire.”

Petyr put his arm around her. “So he is, but he is Robert’s heir as well. -TWOW, Alayne I

and worth noting that he knows who Sansa is (and isn't as loyal to LF as say Oswell):

I never asked to play. The game was too dangerous. One slip and I am dead. "Oswell . . . my lord, Oswell rowed me from King's Landing the night that I escaped. He must know who I am."

"If he's half as clever as a sheep pellet, you would think so. Ser Lothor knows as well. But Oswell has been in my service a long time, and Brune is close-mouthed by nature. Kettleblack watches Brune for me, and Brune watches Kettleblack.

and is a character who has been involved in the story since AGOT, competing in two tourneys already:

• The Hands Tourney (defeats Jory Cassel, ties Aron Santagar, loses to Robar Royce)
• Tourney for Joffrey's Name Day (Dontos Hollard was too drunk to face him)

If interested: Characters Who Know Alayne's Identity

Lyn Corbray

If Sansa wants someone who she knows is likely to win another option would be Lyn Corbray. A big problem though is that unlike just being a "wildcard" like the Mad Mouse (likely trying to kidnap Sansa), Lyn is dangerous. Very dangerous.

If interested: "Gold and Boys and Killing": Ser Lyn Corbray in TWoW

Other Options

Worth noting that competitors (I tried listing them in the Tourney postalso linked above) will only spend 3 years by Sweetrobin's side so it doesn't exclude younger married guys:

The competitors came from all over the Vale, from the mountain valleys and the coast, from Gulltown and the Bloody Gate, even the Three Sisters. Though a few were promised, only three were wed; the eight victors would be expected to spend the next three years at Lord Robert’s side, as his own personal guard (Alayne had suggested seven, like the Kingsguard, but Sweetrobin had insisted that he must have more knights than King Tommen), so older men with wives and children had not been invited. -TWOW, Alayne I

• Mychel Redfort (a talented Vale swordsman, but recently married to Ysilla Royce, he has some drama with Robert's bastard Mya Stone (who Ser Lothor Brune is attracted to)...)
• Distant Relative of Sansa?

Your father's father had no siblings, but his father had a sister who married a younger son of Lord Raymar Royce, of the junior branch. They had three daughters, all of whom wed Vale lordlings. A Waynwood and a Corbray, for certain. The youngest . . . it might have been a Templeton, but . . ." -ASOS, Jon V

• Andar Royce (likely has children but a possibility)
• Hedge Knight (Byron the Beautiful/Morgarth the Merry arrive with the Mad Mouse)

Final Thoughts

While I do think there are plenty of parallels between The Tourney at Harrenhal & this upcoming Vale Tourney, we don't know who/if Lyanna gave her favor out. I do think that there are just way too many things pointing in Ser Lothor Brune's favor for him to not be the leading candidate though. It is worth noting that due to wildcards/betrayals/deaths we might not ever even see the end of this tourney.

If interested: What Can We Learn From The Vale Portion of GRRM's 2003-2004 Outline?

TLDR: Just a look at the potential characters who could wear Sansa's (Alayne) favor during the upcoming Tourney of the Brotherhood of the Winged Knights. While there are several possibilities, I think Ser Lothor Brune stands out among them for numerous reasons:

• He has protected Sansa before (Marillion, continues to show that her heroes arent always what they are like in the stories)
• The narrative structure (he's the one calling Harry an asshole after Harry is rude to her)
• He has proven his skill/valor (Dude's nickname is the Apple-Eater, ask the Fossoways)
• He knows that Alayne = Sansa Stark (when the Mouse tries to kidnap her, etc, he will prob be ready, rip mouse)
• While he works for Littlefinger, he has no actual allegiance to him (for further in the storyline when Sansa needs an ally)