Why is Lyanna Mormont writing to Stannis?

[KingMance]

In Jon's first chapter in ADWD, Stannis is upset (shocking) with the northern lords. He receives a letter from Bear Island from young Lyanna Mormont, stating they only know one king who's name is Stark. Jon has this thought while listening to Stannis grind his teeth and complain:

"Maege Mormont had ridden south with Robb, Jon knew. Her eldest daughter had joined the Young Wolf’s host as well. Even if both of them had died, however, Lady Maege had other daughters, some with children of their own. Had they gone with Robb as well? Surely Lady Maege would have left at least one of the older girls behind as castellan. He did not understand why Lyanna should be writing Stannis, and could not help but wonder if the girl’s answer might have been different if the letter had been sealed with a direwolf instead of a crowned stag, and signed by Jon Stark, Lord of Winterfell."

I checked the wiki, and Maege does have several daughters, with Lyanna being the youngest. I can't seem to find a reason why it's Lyanna, and not one of her older sisters (or their kids) who is the "Lady of Bear Island". Can someone help me out here?

[The Jingo]

The rest are probably dead or imprisoned or else in the field.

[Tucu]

Quote

"Sisters," Alysane Mormont replied, gruff as ever. "Five, we were. All girls. Lyanna is back on Bear Island. Lyra and Jory are with our mother. Dacey was murdered."

They are somewhere with Maege probably plotting revenge.

[Canon Claude]

3 hours ago, Tucu said:

They are somewhere with Maege probably plotting revenge.

So then where was Alysane? Busy getting pregnant by a bear again?

actually, now I hope she was, because then there’s the chance of a truly hilarious moment where Lyanna gets Stannis’ letter, wanders off to find her big sister, hears the bear noises, and quickly decides that she can answer the letter herself.

[Tucu]

1 hour ago, Canon Claude said:

So then where was Alysane? Busy getting pregnant by a bear again?

actually, now I hope she was, because then there’s the chance of a truly hilarious moment where Lyanna gets Stannis’ letter, wanders off to find her big sister, hears the bear noises, and quickly decides that she can answer the letter herself.

Probably preparing troops for this surprisingly well timed attack on the Ironborn:

Quote

And we had other help, unexpected but most welcome, from a daughter of Bear Island. Alysane Mormont, whose men name her the She-Bear, hid fighters inside a gaggle of fishing sloops and took the ironmen unawares where they lay off the strand. Greyjoy’s longships are burned or taken, her crews slain or surrendered. The captains, knights, notable warriors, and others of high birth we shall ransom or make other use of, the rest I mean to hang …

 

[KingMance]

Thanks Tucu. Even on my umpteenth reread, I miss or forget details

[TheLastWolf]

Stannis the mannis Jon's pop. One mare crackpot, no difference 

[Lord Lannister]

For whatever reason she was probably the only Mormont at Bear Island at the moment. Couple that with a child's indiscretion. 

[Lord of Oldstones]

She's maybe legitimate of a known father unlike other "Mormont" girls.

[Lord Varys]

For the same reason why Roose has Ramsay write or sign letters - because they can. Having Lyanna Mormont sign or write that letter sends Stannis the message that they don't give a damn what he has to say. He is so low on their priority list that a little girl can dismiss him.

That changes after Stannis has won the allegiance of the clansmen and Alysane shows up, of course, but back when he was still at CB he was just demanding allegiance and offering nothing in return.

[Canon Claude]

2 hours ago, Lord Varys said:

For the same reason why Roose has Ramsay write or sign letters - because they can. Having Lyanna Mormont sign or write that letter sends Stannis the message that they don't give a damn what he has to say. He is so low on their priority list that a little girl can dismiss him.

That changes after Stannis has won the allegiance of the clansmen and Alysane shows up, of course, but back when he was still at CB he was just demanding allegiance and offering nothing in return.

Didn’t Alysane show up by complete coincidence, though?

[Lord Varys]

2 minutes ago, Canon Claude said:

Didn’t Alysane show up by complete coincidence, though?

Her attack was unexpected by Stannis, but according to his own words Stannis visited all the clansmen in their keeps when he won their loyalty, which means days would have passed before they were all onboard and their armies ready. More than enough time for news about this alliance and their plan to free Deepwood Motte to have reached Bear Island.

The idea that Alysane just happened to attack Asha's ships around the same time as Stannis hit Deepwood just doesn't make much sense. If anybody had attacked Torrhen's Square out of the blue that may have been significant, but this pretty much looks like the Mormonts jumping on Stannis' bandwagon.