He always knew he was different. He wasn't normal, but then again no Time Lord was normal. He had been loomed just like any other child on Gallifrey. He had a single heart that would turn into two after the first time he regenerated. It's just that he was different.
Ever since he was small, his parents tried to treat him like any other. They tried to stay detached, but his mother had little success at that. The thing was she was not Gallifreyan. She was human or otherwise known to his people, an ape descendant. It was hard for a human especially a female to be detached to her son though he was more of an adopted son really. He was not born. He was loomed. The genes of his "parents" combined to make him.
As a youngster, his differences didn't make him stand out. He did hear the whispers though. Not everyone accepted him. The more hateful people called him names such as "mongrel", "half-breed", and "outsider". When he asked his parents about it, his father told him to pay no attention to it. So he ignored the whispers.
It came about when he turned seven. Ever since he was younger, he wanted to be a Time Lord and go to the academy. He knew as everyone on Gallifrey knew that Time Lord abilities manifested at the age of seven and if they turned up the lucky child went to the academy at eight years of age. His father was a Time Lord too and he regaled his son with tales of being a Lord of Time. The young Doctor, then Theta, would gape in awe and his eyes would shine with hero worship. His father would grin and would tell him stories until his mother said that it was time for bed.
Finally, his seventh life day arrived. He was all ready for those special abilities to turn up. The day passed and no luck. Several months passed and his parents told him to give up hope. He wasn't going to be a Time Lord. Being a stubborn child, he didn't give up. He just knew he was supposed to be a Time Lord. It was his destiny.
After half a year had passed, all of his friends had received their gift. He started to lose hope. Then, that fateful day came. When his abilities finally appeared in him, they came in force. A storm of emotions, feelings, and thoughts assailed him. He thought he would sink under that flood. Life was never the same again.