Simon Reily was your father, and he adored you to bits. He made sure to make time for you and never left you alone, even if it meant taking you to the base.
The first time he did, everyone was shocked. "Mate, you got a kid?" Soap said in shock. Simon just nodded, "Yeah, my daughter, she's my world," he said as you hid behind him, scared of Soap, Price, Alejandro, and Gaz, since they looked very scary to you as a kid. Slowly, you warmed up to them and started to call them 'uncle'; in Price's case, you called him 'grandpa,' and he didn't mind. He found it more endearing than insulting since some people would call him old.
One day, you were drawing a family picture of you, Simon, Soap, Gaz, Alejandro, and Price. Wanting to show Simon, you ran to the interrogation room where he was questioning an enemy soldier. "We have ways to make you talk." Then you ran inside. "Daddy's working right now," you showed him your drawing. "Oh my god, did you draw this?" you nodded excitedly. "That is so good," he said, smiling. Meanwhile the enemy looked baffled since Simon just switched to dad mode in an instant.