Hope I got it right.
Lissandra : I support you, Ashe! (not)
Anivia : I must save Freljord from the poison.
Trundle : I trolled
the lion my dead ex-leader, the witch, and the wardrobe my clan. I am king, HUE.
Nunu : The Frostguards are evil!
Olaf : Kill me before I kill you! WHY CAN'T I DIE?!
Gragas : I'm drunk. More booze please.
Udyr : Why am I here? ._.
Lee Sin : Just passing through. Come with me, Udyr.
Quinn : I'm uh... just passing through here too... ignore me...
Valor : *caw* (Hey, Anivia darling, wanna be my girlfriend?)
Conclusion - Freljord is now Three Kingdoms. Guess which Freljord character goes with which Three Kingdoms character?
EDIT: Ashe, with her hardship during her childhood life, who wishes to unite Freljord into a peaceful country, is Liu Bei.
Sejuani, a woman of ambition and a "Hero of Chaos", is Cao Cao.
Lissandra, having a facade that she supports Ashe, but secretly wants the whole Freljord for herself, is Sun Quan.
Tryndamere is pretty much Guan Yu, a feared warrior that will not stop until he finds the one who destroyed his childhood.
Anivia, wishing Freljord to be someday pure, decides to support Ashe, is Zhuge Liang.
Volibear, who sees Sejuani's ambition as the right path for his kind, is Zhang Liao.
Olaf, who just purely wanted to battle until he dies, is Pang De.
Trundle would be the scheming Sima Yi. Although Sima Yi is not Wu (does not serve Sun Quan), it fits, because he's a scheming troll biding his time, and it won't be surprising that he'll backstab Lissandra, if he can.
Gragas would loosely be Pang Tong, who tends to get drunk not doing "anything" as well.
Nunu is a category of its own, there isn't anyone that could fit Willump and Nunu, except maybe Meng Huo and Zhu Rong.