This is kinda a general question, but can you elaborate on Ranji and the twins’ relationship? How did he go from being a stranger to a parent figure for them? Did he have a lot of trouble getting through to them at first?
I think I've mentioned this somewhere on some blog or another, but I can elaborate on it again now!
Ranji was originally a wealthy, famous chef in India and had a loving wife and kids. He was in the pinnacle of his life, but then a car accident killed his wife and children. Ranji fell into a really deep depression that cost him his job, and he was barely living for several months.
This is important to note because timing is key when it comes to Ranji and the twins, because the Twins came into Ranji’s life during a very critical point in Ranji’s grief, and while it might not have been healthy, Ranji latched on to these homeless, basking children (Glenn included) after being thoroughly wowed by their shows. Once he learned they were homeless, Ranji offered them his home as shelter for free, and even started cooking for them again--which he had stopped doing for the most part during the months in between his first family dying and meeting his second family. Taking care of them brought Ranji out of the rut he was in, and he was able to actually start living again. In a way, the twins and Glenn saved his life in this regard, which is why he becomes so attached to them so quickly.
The twins weren’t as quick to trust Ranji, however. Kokichi found him to be strange and was really skeptical, but the twins learning about his family probably softens them up to him now that they can understand why Ranji is being so kind to them. Considering how he takes care of them for a long time and makes them all food for free, they start trusting in his kindness and to be honest, they probably latch on to him too because they never had a proper father figure before. They never had a father that loved them so warmly and gently, someone who cherished them as children. Ranji reminded them that they are children, and spoiled them with treats, gifts, and love.
When Kokichi and Kurochi decided it was time to go, Ranji and the twins had especially gotten close as family, to the point where Ranji adopted them and liquidated all of his assets to join them, and further take care of them. He buys them laptops and cell phones and other things, so they could have some semblance of an education online and able to communicate better with each other. Ranji also probably makes a hefty income in later countries because he can actually get hired as a chef, even if it’s part time. Not that it mattered much to the twins if he could get them money or not--by that point, they loved him as their dad, and wanted him around regardless.