Remember Gendry Waters?
He was Arya's faithful travel companion long before the Hound.
They had some good times.
And grew very close.
But then Melisandre took Gendry away and seduced him and freaking LEECHED him.
She and Stannis used Gendry's half-royal Baratheon blood in a spell to put a stop to the "usurpers" Balon Greyjoy, Robb Stark and Joffrey Baratheon. Which seems to be working pretty well so far...
So it's not like Gendry is unimportant - to the show in general and to Arya in particular. Which makes it all the more frustrating that he is NOWHERE TO BE FOUND.
The last time we saw Gendry, Davos was helping him escape Stannis and Melisandre, and their plans to burn him alive, by putting him in a boat.
Davos gave Gendry three pieces of advice:
1. Head for King's Landing.
2. Don't drink the seawater.
3. Don't fall out.