important note; my portrayal of thomas is fairly canon divergent. first of all, i write thomas strictly pre-series by default and i will not write him in a romantic or sexual relationship with neither canon nor oc characters. my thomas will therefore not have a child if i ever do write him in later seasons, nor will he have been with grace at any point nor any of the other characters he's canonically had a relationship with on the show...

thomas michael shelby was born in small heath, birmingham, england in 1890. he's the second oldest son of an irish immigrant father and a mother of romani extraction. he was the son of arthur shelby, sr. the younger brother of arthur shelby, and older brother to john shelby, ada thorne, and finn shelby. the shelby brothers were also kin to the lee family on their mother's side. the brothers were involved with the organized crime gang, the peaky blinders. thomas was in love with a girl named greta jurossi before the first world war. however, gretta grew sick, and thomas stayed by her bedside for three months before she passed away and he went to war.

both thomas, arthur and john were drafted into the british army during world war one, and thomas served as a sapper or a tunneller, a volunteer digging treacherous tunnels covertly, in order to place enormous amount of explosives beneath enemy lines, a tactic used several times in the war to devastating effect. his actions at the 1914 battle of mons saved thousands of allied lives, and he was also recognized for his bravery at the battle of the somme and the battle of verdun. his flawless conduct earned him the military medal and the distinguished conduct medal, which he threw away in the "cut". thomas was also a member of the small heath rifles at the rank of sergeant major – a non-commissioned officer in charge of well-being, morale and training of the entire unit (all other sergeants and corporals answering to him as well as to the actual commanding officers). his flawless conduct in this role (made even more difficult on account of his youth at the time) earned him unwavering respect both from members of his unit and other veterans alike and cemented his reputation in the streets.

there was a drastic personality shift before and after his experiences in the war. after the war, he began experiencing symptoms of post-traumatic stress disorder. after returning home from the war, thomas became a respected figure in the neighborhood. his brother, arthur, became the leader of the peaky blinders, but he relied on tommy to be the brains behind his criminal enterprise.