Liam O'Connor is one of the three protagonists of the TimeRiders series. He is the field operative of the team, travelling in time to observe and then prevent time contamination.
He is a support unit developed by Waldstein and made to resemble an older version of Waldstein's deceased son, Gabriel. The original backstory fabricated for him was that he almost died on the Titanic in 1912 but was saved by Foster.
Liam is programmed with memories of living in the late 1800s and early 1900s. He used to believe that he lived in Cork, Ireland before becoming a steward aboard the Titanic in 1912, where he became trapped on Deck E while trying to help people escape. He supposedly met Foster there, who appeared out of nowhere, and offered his hand to him, telling him he could save him. After taking Foster's hand he awoke in New York in 2001, at the beginning of TimeRiders.
In reality, Liam was developed by Waldstein in the image of his son, Gabriel, and grown in a tube until he reached the age of approximately 16 before being dispatched back to 2001.
After being saved from the Titanic, Liam accepts his role as one of the TimeRiders. For a training routine he goes back in time with Foster and Bob to delay JFK's assassination but their training is cut short by a time wave. He travels back to the 1940's where Paul Kramer's actions have led Germany to victory in WW2. He is then taken prisoner and taken to a concentration camp. Separated from Bob, he misses all return windows sent by Sal and Maddy. Liam is then rescued by Bob, who has many followers who think he is an angel of the Lord. Eventually Liam and Bob leave a message for Maddy and Sal in the Museum near all the visitors books, telling them where to open a time window. They successfully get back, right in the middle of an attack from the "human" race. He helps get rid of them for long enough to open up another time window and are sent back again to where Kramer entered. Bob stops Kramer, but is damaged beyond repair. Liam is forced to cut out and retrieve Bob's silicon computer chip, a gruesome job for Liam. He comes back and helps clean up the bunker. Sal said in her notebook that "he looks older and grown up than before his mission."
Day of the Predator Edit
The Doomsday Code Edit
The Eternal War Edit
Gates of Rome Edit
City of Shadows Edit
The Pirate Kings Edit
The Mayan Prophecy Edit
The Infinity Cage Edit
It is revealed that Liam is, in fact, a clone of Dr. Roald Waldstein's deceased son, Gabriel. Along with this revelation comes the reveal that Foster was the "Liam" of the first and original Time Riders group that met disaster. Being the only survivor, Liam 1.0 had his name changed to "Foster" to be the guide and teacher for the new group, Liam (2.0), Maddy and Sal. So Foster (Liam 1.0) and Liam 2.0 are both cloned from the DNA of the deceased Gabriel Waldstein.
Liam and Maddy grow close over the course of the series, developing a sibling-like bond which grows even stronger when they discover they have no family but each other, and then stronger still after Sal's death. They part sadly in the final novel's opening chapters, and Maddy decides not to join him in the past.
Liam and Sal also have a close relationship, with Sal observing that he is almost like an older brother to her (and then deciding he is just that when she discovers the nature of their 'births'). Liam regularly lifts her mood and strives to protect her in difficult situations. Sal grows increasingly jaded after discovering that she is a support unit, growing paranoid and angry towards Liam, which upsets and frustrates him. Her death is a result of this disconnect between them. Later, in the final novel, the two manage to patch up their differences, with Sal seeing Liam again in death and asking him to do all he can to break humanity from the infinity cage.
Bob interacts with Liam the most of the team, being in his company constantly while on field missions. This leads to the two having a close friendship, even as far as Bob being able to alter his mission priorities to save Liam, and then choosing to base his new simulations of emotions on Liam as well as the other TimeRiders.
Like Bob, Becks spends a lot of time around Liam, who was even the one to name her. She also strives to protect him and takes emotional cues from him. Eventually, she realises she has developed some kind of emotional, perhaps romantic, attachment to him and chooses to stay with him in his time.