Try to "win" the Game of Thrones by Episode 3
If Game of Thrones was a truly sandbox game, discuss how you would "win" the Whitehill's struggle.
Personally, I'd:
Kidnap Gwyn Whitehall when she visits the funeral. Its a dick move but so is getting Ethan stabbed. She was attending the funeral without her father's knowledge, so I would keep her kidnapping a secret and stash her somewhere. Bargaining chip for Ryon's release. All her father will know is she is missing, hopefully enough time to pull off the rest of the plot.
A few days before Gryff arrives at Ironrath, poison all of the guard's wine. Have the poison take effect when they are sleeping, go in and execute the sentries and bar the gates to the barracks.
Dress up your own soldiers in Whitehill armour and surprise Gryff when he arrives. Now you have his son and firstborn daughter as hostage.
Promise the Glenmore's half of the forest in exchange for armed support, either garrison your own lands or go on the offensive against the Whitehills depending on how it plays out.
Tax the smallfolk a decent amount as you'll need it to support your efforts, not too much to be seen as harsh.
Double your efforts on harvesting and manufacturing the ironwood. Once everything is settled, send a surplus shipment of ironwood to King's Landing (for the same price of course). The Lannister's would be appreciative as they desperately need it for their navy and would be more than willing to allow the status quo of Forrester supply.
With the Lannister's happy, the situation stabilized, Ramsay Snow would have no real reason to visit again as well.
Trade Ryon for Gwyn, keep Gryff to ensure the peace.
When Asher and Malcolm arrive with their mercenaries, use them and the profits made from selling Ironwood to supply an army. March upon the Whitehill's land with Glenmore support - execute every male Whitehill you find in retribution for Ethan. Gwyn and by extension Asher might be a bit pissed, but so be it.
Get Asher and Gwyn to wed. As Gwyn is the last of the Whitehill lineage, they hold the rights to rule Whitehill land. The next heir of Whitehill shall be a Forrester. Exile/execute the bannermen who were loyal to the Whitehills and give your loyal mercenaries and Forrester nobles all of their lands. The common folk might resist the change at first, but I doubt it would be for long (considering the Whitehills don't seem like the benevolent ruler type.)
At the end, you have appeased the Lannister's, integrated the Whitehills, built a powerful ally with the Glenmores (which would have a vested interest in keeping their ironwood profits safe) and expanded your house to TWO landed branches (the Rodrik and Asher lineages). Ramsay Bolton would be too occupied and as long as you continue your Ironwood shipments he would have no reason to intervene. Hell, he might even appreciate your level of brutality in dealing with the situation. Yara and the Ironborn hold Deepwood Motte with 30 longships and the accompanying ironborn, you can send your mercenaries to siege it to get on Roose Bolton's good side (Deepwood Motte is very close to Ironrath and they would likely not expect a mercenary army from Essos, their defenses would be lowered). Ramsay would have no choice but to listen to his father.
Comments
I don't think you should keep Gryff though. The situation is settled. That's just as much a dick move to them as taking Ryon was to us. The Forresters are better than them.
House before Honor, Iron from Ice. The Forresters and the Whitehills have been rivals for generations, that sort of feud doesn't end. Besides, to have Highpoint and the Whitehill lands inherited through Gwyn and by extension Asher, there would have to be no male descendant left. Not only would I keep Gryff but have him executed once the Forresters are brought to ruin.
We haven't even met Gryff yet. He could be a pretty cool character.
There's ALWAYS a male descendant. It may be a second or third cousin, but given how thoroughly the people of Westeros keep their geneologies, you'd probably have to kill hundreds of men before you ran our of heirs.
In primogeniture, the current ruler's direct descendants are counted before any brothers and sisters (male heirs considered over female first). A distant relative could claim the rule illegitimate, but without any army or lands to gain influence and support from, they would need support from an outside source. With the Lannister's appeased, Boltons busy with both the Ironborn and quelling disloyalty, there would be no one to contest. Might is right in this case.