Wilson was walking backwards, which meant he didn't immediately see the situation as he and Phale came upon it.

"Then you take the gerbil and..."

Something in his lover's shift of expression caused him to stop in mid sentence and turn around to see what Phale was looking at over his shoulder.

"Bel!" Wilson said immediately and with the common sense that God gave a squirrel, the young doctor darted towards his young friend's side.