My 9 months old has cries a lot without her mother, he is very smart to know when her mother is leaving during sleep for bathroom and check to see if someone is there, cries when he sees me.Same case when holding him in arms with me and her. Although he is like that with everyone but with me he is special cry baby. It is sad and frustrating because we had same off-time from work and give him time. I had started work in recent weeks, my mrs is terminally ill and get really tired and hands me baby in frustration and anger but the baby just start crying. Lately it has been embarrassing for me as of why he does that, does it has anything to do with my mrs letting him have her milk all night or sleeping next to him. (out of crib), i don't mind that baby is attached to mom, it's why he cries and run away when i am trying to calm him down?
This is totally normal during this age. Babies tend to have a separation anxiety at this age approximately.
So he thinks now that you are going to de-attach him from his mom, especially if he is a breastfed baby then this will get harder.
You have to make him love you more by playing with him games he like, singing for him, or giving him some toys, maybe feeding him, or giving him his bottle, take him for walks, etc... This might take few time bit he will get used soon.