Believing is Seeing.
I believe you.
It was the closest declaration of love that Allison could get to say without actually saying, "I love you".
Allison doesn't have to utter her secret love and devotion towards Lydia because her eyes say it all and they say it back, with a silent thank you.
When they get on the bus looking to catch up on much needed sleep, they pair off; Stiles with Scott and Lydia with Allison.
Allison takes it upon herself to hold Lydia closer in the bus seat, in means of letting Lydia know that she will protect her at all costs.
When Allison looks over to see Scott and Stiles asleep in their own seat, Lydia grumbles out, "I think we are okay to sleep now, my beautiful knight. Go to sleep now. Protect everyone later." Ducking her head back into the crook of Allison's neck giving a light kiss to the skin there letting sleep over take her.
Allison gave one more look around before she spotted Isaac and Boyd climbing on to the bus as well. She gives them a small smile as they pass by to find their own places to rest for the night.
With a kiss to the crown of Lydia's head, Allison finds peace of mind and doses off to sleep with her queen in her mind and her heart.