They met when Laurent visited The Denali Coven in fascination of their lifestyle. They were attracted to one another, and she was helping him adjust to the vegetarian diet which he was struggling to abide by. Their bond was strong enough that it was implied he was likely to return to Irina after fulfilling his favour for Victoria. He was killed before any deeper feelings were developed.
These two obviously had a strong attachment since when Laurent died, Irina blamed the Cullens. She wrongly accused them for creating Renesmee, who she believed to be an immortal child; she also was the one who brought that up with the Volturi, and later she was murdered as punishment for false report.
- "I like Tanya very much. And her sister Irina even more... I've never stayed in one place for so long before, and I enjoy the advantages, the novelty of it."
Laurent was a French man created by a vampire named Boris after being introduced to immortality and the benefits of being a vampire. After growing tired of his playful lifestyle, he left on his own to find more powerful vampires. He eventually wound up in James's coven, consisting of James and Victoria.
When James got curious with the coven up North, they decided to check them out, and subsequently met the Cullens. When James started tracking Bella Swan, he became embarrassed by his actions and left James's coven for self-preservation.
- "He wanted to be like us, to live in peace with humans. With me."
- ―Irina on Laurent.[src]
Irina was a peasant girl who became the third vampire created by Sasha, when she wanted to add a sister to her daughters, Tanya and Kate. They loved each other so deeply that it devastated her and her sisters when they saw her burn.
To find comfort, she sought the company of men, both of vampire and human. Like her sisters, she preferred human; however, as they got closer to the humans, she always ended up killing them. As the centuries passed, she found the smaller losses too unbearable, but could not bear to keep her distance without feeling the loneliness of her deceased mother. After Tanya discovered that animal blood could bring the nutrition for them without weakening their ability to resist human blood, Irina and her sisters started practicing feeding only on animal blood, which improved her self-control overtime.
After being told of the Cullens' "cousins" in Denali, Laurent decided to visit the Denali coven, interested in trying the Cullen's lifestyle and wanted to see what it was like. After getting to know the Denali clan better, Laurent and Irina developed an infatuation of each other. He tried to adjust to "vegetarianism", but found it very hard and occasionally cheated.
- Main article: New Moon
Before their courtship could move on to the new stage, Victoria tracked him down to Alaska, and asked him to return to Forks as a favor to her: Victoria wanted to kill Bella because Edward killed James, her mate. And for retribution, she plotted to kill Bella to make him feel the same pain that she felt.
Laurent agreed and returned to Forks, and discovered that Bella was no longer under the Cullens' protection. While hunting in the woods, he came across Bella in the meadow and explained how he went up to Denali and the hardship of animal blood. He also told Bella that he was here as a favor to Victoria to see how easy it would be to get to her. Because he was thirsty, he decided to kill her himself, and told her that he was doing her a favor, pointing that he will kill her very quickly whereas Victoria was planning to slowly and painfully torture her to death. But before he could touch her, the Uley pack emerged and eventually killed him in the woods.
Irina heard of his death sometime after the Cullens returned to Forks.
- Main article: Eclipse
The Cullens called the Denali coven to help them defend themselves against an army of newborn vampires, not realizing the extent of Irina's feelings for her deceased mate. A grieving Irina demanded to let her fight the wolf pack to avenge Laurent in exchange for the Denalis' aid. Carlisle refused and so lost their help, along with their temporary disbandment.
- Main article: Breaking Dawn
Irina didn't attend Bella and Edward's wedding due to her hatred of the wolves and the Cullens' tolerance of them. In the movie, she attends briefly but leaves when she sees Seth Clearwater, a new member of the pack that killed Laurent.
Four months after this event, Bella's transformation and Renesmee's birth, Irina came to Forks to reconcile with the Cullens. However, once she arrived, she saw Bella, Jacob, and Renesmee together, and Irina mistook Renesmee for an immortal child. Still grieving for Laurent and also for her mother, who died due to the Immortal Children, she reported what she had seen to the Volturi.
On December 31st, the Volturi came to Forks with Irina to destroy the Cullen family, but when they realized that Irina was wrong about her accusation, Irina openly accepted her punishment and apologized to the Cullens. Caius killed her for providing the Volturi with false information and as a ploy to provoke a battle between the Volturi and the Cullens. Grief over the murder of their sister caused Tanya and Kate to attempt an attack on the Volturi. However, they were prevented from avenging Irina.