An Irish citizen and nationalist, Doyle was a former Captain in the IRA who used the moniker "Valhalla". At some point in his life, he met Chloe Donaghy, with whom he fell in love and had a son, named Declan. Donaghy attempted to abort Declan before he was born by ingesting pills, but Doyle stopped her and imprisoned her until Declan was born with the help of his nanny Louise Thatcher. He then paid Donaghy for giving birth to Declan and sent her on her way, unknowingly earning her wrath.