I literally wrote a guide on faeries (url is in my signature). Pet auto heals people under 80% within 21y, so the only part where you need to do anything is to make your pet heal above 80% or outside 21y.

My conclusion was the optimal setup was to keep the tank as your main target, use a macro to spam Embrace, and put attacks on macros so that you don't have to change targets (if you have the enemy targeted while spamming Embrace, Eos heals herself).