A plastic surgeon in wealthy Newport Beach, California, Neil is the father of Summer Roberts. He was married to Summer's mother until his daughter was 13 years old, when Summer's mother left for unexplained reasons. This was the same time that Luke Ward had his 13th Birthday Party at the same that Seth had his Bar Mitzvah. Summer had RSVP'd to Seth that she was going to come to his Bar Mitzvah, but she wanted to go to Luke's party instead. Summer's parents wouldn't let her go to Luke's due to her prior engagement, so she locked herself in her room for days, and when she came out her mother had left. No one came to Seth's Bar Mitzvah as they all went to Luke's party.
Scarcely present since the beginning of the series, Neil is seen by the middle of the third season beginning to develop a relationship with the widowed and newly economically-challenged Julie Cooper, as he alludes to an unraveling marriage to Summer's stepmother. Neil and Julie then get engaged. But after the death of Marissa, Julie becomes addicted to medication pills and Neil is seen by Kaitlin Cooper with his ex-wife (the so-called stepmonster). Neil and Julie break up and Neil moves to Seattle to work at Seattle Grace Hospital (home of Grey's Anatomy).
In a flashforward, his only daughter Summer, eventually ends up marrying Seth. However, Dr. Roberts did not appear in the wedding, despite his paternal love for Summer. Subsequently, Summer walked alone down the aisle, but she did not appear to be affected negatively by the absence of her father.