Lyle had been thinking about something during the week before the attack on the enemy hideouts. Upon leaving Nicholas's office and the headquarters, he went back home.
He had actually forgotten about something very important. As a perfect hybrid, he didn't have the weakness that normal vampires had, but he also didn't get the benefit of being able to heal using blood.
Not healing wouldn't be exactly correct, actually.
Hybrids could drink blood in order to make the healing process continue without exhausting themselves, and Lyle had done so in the past. During a difficult situation, when he didn't have any healing potions or salves, he would drink blood in order to replenish the blood he had lost, which would allow his body's healing factor to continue healing him. The speed of which the healing would be improved would be marginal, perhaps about 30%, which was much worse compared to using a healing potion or salve.