Just to give you guys an update and fill you in on some of the details of the story:
I've updated the timeline so that the invading lord attacks early in the fall, as the harvest is being gathered. The idea is to prevent the defending lord from stockpiling his food stores ahead of winter and preventing a long siege. As I said before, the attacking lord knows he's going to face a very tough fight early in the spring, on the heels of winter, and he needs to get his house in order, so to speak.
The defending lord has vassals of his own. It's important to the attacking lord to have all this sorted out before the spring, so that when he calls his banners (or whatever, I'm sure I'm butchering the vernacular), they respond.
There are some supernatural things going on behind the scenes. Namely, a freak winter storm that breaks out soon after the siege begins. It nearly breaks the siege, but makes everyone involved pretty miserable. On the plus side, as far as the attackers are concerned, it makes the night watches pretty difficult.
The defending lord gets a messenger out through the sally port, who heads off to call a nearby lord to action. It's the realization that the attacking lord is about to get crushed between the walls of the castle and an attacking army that prompts Jenya to action.
The motivation for Jenya is simple. Her father, the defending lord, has been sexually abusing her for about three years prior to this. She's desperate. When she realizes that the attacking lord is going to lose (and her situation will continue), she looses it. She's desperate. She will do anything at this point to make it stop, including betraying the castle.
The guard doesn't particularly desire Jenya, but she is exceptionally persuasive and attractive. It's hard to tell a voluptuous young princess no.
In times of peace, the guard's normal duties involve protecting Jenya. He sleeps in the anteroom of her quarters. He is supposed to be 'her' man, but he's watched as her father has come in night after night and done nothing while she's been violated. True, there isn't really much he could do about it, but try telling Jenya that.
So there's a lot of built up rage in her, and it all comes out on him. It's important to the development of the character that she kill him.
Despite the above, he is loyal to his lord.
The original idea was that the sally port led, not to a moat, but into the mountainside which the castle is built into. It could exit some distance from the castle itself. The attacking lord knows about the port, but has been unable to find the entrance. Besides, sending men to attack a locked gate single-file would be suicide.
But, it isn't critical to the story that there be a sally port at all. I think it's neat, but I'm not married to the idea.
Here's what is critical to the story:
1. Jenya has to betray the castle in some way. She needs to be instrumental to the taking of it. In the process, she kills one, maybe two guards.
2. The attacking and defending lords meet in battle, originally in front of the keep itself. The attacking lord kills Jenya's father. Jenya witnesses this.
3. Jenya is captured, and brought before the attacking lord.
That's really all that has to happen for the story to unfold the way I want it to. If it's more believable, I can have her throw a rope over the side. I'm open for ideas!