Rahul was a man who lost his sister, Asha Chandra, in mysterious circumstances. He sought to find out what had happened to her.
Spending years keeping up with alien conspiracy theories and monitoring energy readings in Sheffield, he eventually found the pod again that emitted the creature which stole his sister. After paying his van driver to help deliver the pod to his warehouse, he spent the night waiting for it to open, setting up cameras to monitor the object.
While waiting, he made a video explaining why he took the pod and uploaded it to his computer for others to find should he ever die searching for his sister.
When the pod finally opened, he confronted the creature inside, Tzim-Sha, demanding to know what he did with his sister. The alien advanced on him, stating he would never know before freezing him to death.
The Thirteenth Doctor later found his corpse, with Grace, Graham, Ryan and Yas. They discovered that Tzim-Sha had stolen a tooth from Rahul as a trophy. (TV: The Woman Who Fell to Earth)