The mother is also the same product of the Chimera family that the ML let go...
When the mother escaped her capturer, the 2 siblings were separated... the Mother is looking her other son(who is w/ Omi) while telling the MC to not go out because his a chimera & will be killed (Omi's & others job).
When the mother found her missing older son, maybe, her capturer also found her so she left the MC to find his older brother & for his safety(this last sentence is what I think)
The mother is also the same product of the Chimera family that the ML let go...
When the mother escaped her capturer, the 2 siblings were separated... the Mother is looking her other son(who is w/ Omi) while telling the MC to not go out because his a chimera & will be killed (Omi's & others job).
When the mother found her missing older son, maybe, her capturer also found her so she left the MC to find his older brother & for his safety(this last sentence is what I think)