Alvin had a rocky relationship with his partner, Officer Adam Ruzek. This was largely due to Ruzek's inexperience and cockiness. However, the two genuinely care for one another.
At one point, Alvin had served in the military as part of a Special Response Team in Italy. It is revealed that he had seen some action in Italy while serving there.
Later he joined the CPD working alongside Sergeant Hank Voight, Jimmy Shi, and Ruzek's father. Alvin and Voight shared a close partnership and friendship. Alvin had an unwavering loyalty to Voight and would do whatever he asked off the books.
He was an expert at undercover stakeouts. His dedication was evident by the fact that he wore adult diapers to make sure he didn't miss his targets. This began after a particularly nasty incident where a B&E team got away when he went to relieve himself.
It is revealed that Alvin had an estranged relationship with his wife, who had made him move into the garage. Despite the tension in his marriage, Alvin still maintained a close relationship with his daughter, Lexi.
When Lexi was blamed for having marijuana in her locker (stored there by a boyfriend), Alvin was quick to help his daughter out. Even though she was suspended from school, the two had a father/daughter dance in the garage.
When an ill-fated party ended in a gang member's shooting death, Lexi was the only witness. Alvin tried to prevent Lexi from becoming a witness as it would endanger her life. However, when the shooter refused to confess, Lexi volunteered.
In season 2, Antonio told Ruzek that Olinsky already had full pension but refused to retire.
In Season 4, when Adam went undercover, Alvin began to partner with Kim Burgess. He wasn't happy with the pairing and Kim was upset at his attitude towards her. Trudy told Kim that this was because he never really accepted women as equals in the force, but Alvin told Hank later on that he didn't want to work with Kim because she was full of hope and that they get the worst cases, and this would break her heart and he couldn't be around when it happened. Voight told him to give her a chance because she's good.
In Tough Enough, he told her to keep her feelings out of interviews. He then asked her why she deserved to be in Intelligence, to which she replied that she'd been shot, had the most arrests and been in the worst cases. He then told her that good detectives don't 'boast'. She said he asked but he replies "I don't know if you're tough enough for Intelligence". She told him to "get ready to eat some crow, Al."
Alvin continued to be distant with Kim, constantly picking on her about her mistakes when she was new. But she proved herself a number of times, and he respected her for it.