Lol, Shane being a mother to the Redcloaks would be great! Speaking of moms though, how about Shane's own mother? Shane's little flashback story about her just always seemed so cute to me, and she's honestly just a wonderful mother! But then she also foreshadows things.
"This is the prince of Stetriol; he'll never bow to a mere snake." (*Cough* Gerathon)
"You don't want to hurt snakes for being snakes, do you?" (Snakes = Greencloaks?)
I can't help but wonder if Shane actually thought of her at times throughout the main series, or if he feels like she would be disappointed to see how he turned out.
I've been trying for a while to figure out just how Shane's guilt builds up. I'm not sure if a small part of it has always secretly been there, but by Book of Shane #2 and The Evertree, Shane's definitely having regrets. I think Achi's story of what happened to his village, plus the deaths of Drina, Gar, and Renneg, opened his eyes to the war's destruction.
If I can add my own list of songs, how about The Scientist (Coldplay) for Shabeke, Dream Come True (Casey and Jeff Williams) which can work for either Shya or ShanexTalon, and Cold (by the Williams again) which I've always imagined from Stead's perspective. Words Fail is really good though!