I am about to propose an idea to a friend of mine who plays a Wizard, and whom we have finally convinced should get his familiar up and running. (I play a Cleric in this party). He is concerned that his owl with only 1 HP will too easily die. This is a valid concern based on the experiences we had in our first D&D 5e campaign; my brother's wizard's owl familiar died with some frequency. (This question was inspired by a previous question about familiars.)
I am about to propose that he not worry, since when I cast aid on the party, I can include his familiar. What I am not sure of is whether the familiar (who I think qualifies) to receive the temporary hit points for aid, can be healed if it takes damage less than lethal.
The aid spell says:
Your spell bolsters your allies with toughness and resolve. Choose up to three creatures within range. Each target’s hit point maximum and current hit points increase by 5 for the duration. (Basic Rules, p. 83)
When my cleric casts aid, can my wizard ally's owl familiar get 5 temporary hit points and be healed if it takes damage?
This would improve its chances of survival considerably.
Illustration: I cast aid, owl has 6 HP (1+ 5 Temp). Owl takes 4 HP damage. Can I heal it back up to 6 HP after or during the battle? I am not sure if these bonus HP are like temporary HP, or not.