Keith was born in Glasgow he was placed into care by his parents when he was 18 he tried to get in contact with them however they had started a new family and didnt want anything to do with him.
Keith first joined the group when he asked if he could help Zack Zindine after his mate Becky Miles had helped him understand why Scott Curtis and the other members of the group wanted to help Kim Knight As a favour to Becky Miles he wanted Keith Rainer to help her when Oasis Care was after her. At this time Keith Rainer was living with Zack Zindine in Plymouth He was known as a strong member in the team. The same year he found himself fighting a clone of himself which he was able to beat up and win the fight with.
In 2003 he had fallen in love with Lizzy Smith and she soon became a member of the group with Keith Rainer.
Keith wanted to try and fix things with his oldest daugter Rachel Rainer he took off for a total of a year this time he spend with her. Lizzy Smith guessed it was over between them.
Keith Rainer came back and himself and Lizzy Smith went back out with each other. There were rumour near the end of that year he was going with Maria Hart lover who at the time was Emily Matters but nothing was ever proven.
Keith Rainer had started to put up Zoe O'Chapel in his flat at Torquay where he was now living with himself and Lizzy Smith. Later on that year he was caught having sex with Emily Matters. Zoe O'Chapel went right away and told Maria Hart and Lizzy Smith. Right after this Keith Rainer and Emily Matters took off into the darkness and no one heard from them again for a year. it then came out that Andy Bywater who had also fleed when his feelings for Roy Dart didnt work out. He had been putting up Keith Rainer and Emily Matters down in Lowerstoft
When Keith Rainer moved back down he was not gave a very happy welcome and the trust between Maria Hart and Keith Rainer was very low. Also Stacy Hart broke his nose but he did not press charges. When this all started up Steph Colledge took care to sort the pair of them out. This was also in order to save the River Group for breaking up. Later on that year Keith had a visit from his daugther Rachel Rainer who wanted to know why even when she had moved back down to Kingsbridge he had not seen her. Keith soon had Rachel living with him. He then found that Rachel Rainer was going to be having a baby making him a grandad at the age of 26. He soon ended up once again getting back with Lizzy Smith and found himself married very soon afterwards. He then had a daugther who he called Emily Smith.
2008Keith now kept to being a family man but felt bad when Rachel Rainer started going off the walls just like he did when he was her age. He found this hard and almost lost his daugthers because of this. Later on that year Rachel Rainer started making it easier for Keith Rainer.