Platinum is a descendant of the prestigious Berlitz family, which is a wealthy clan in Sinnoh with a history of more than 200 years, producing fine scholars in every generation. A family tradition calls for each individual to travel to the summit of Mt. Coronet, and collect a special material to create an accessory bearing the family crest. Like her father Sir Berlitz, she is acquainted with Prof. Rowan and has worked as his assistant before she set out on her journey, allowing her to know a lot about Pokemon.
Proud and arrogant, Platinum comes off as a spoilt girl, and only spends her nights at top-class luxurious hotels. She did not find it necessary to reveal her name to people of a lower class, as taught by her butler Sebastian, and thus refused to tell it to Dia and Pearl, whom she mistook as her bodyguards due to a mutual misunderstanding. However, Platinum actually has the heart of an innocent child underneath her perky exterior, and can sometimes come off as goofy even. As she weathered through various adventures under the support of Dia and Pearl, she gradually came to appreciate their presence, shared her glory of victory with them when she won the Super Contest, and even started addressing them by their first names after the incident at Veilstone City.
According to Platinum herself, she reads at least 10 books each day since her childhood, and as a result, is very knowledgeable in many aspects, a reflection of the virtue she represents: knowledge, making her the most associated with Uxie of the Sinnoh lake trio, the knowledge Pokemon. She is almost like a walking encyclopaedia, which added to Dia and Pearl's misconception that she was a very professional tour guide at the beginning. However, Platinum believes that learning through first-hand practice is much more effective and interesting, and thus constantly wishes to try out and experience everything that comes along. It is therefore no surprise that she has decided to take on both gym and contest challenges, on top of many other things she desires to explore. She easily gets along with people due to her genuine interest and enthusiasm, and is acquainted with Cynthia, who has personally taught her about battling at Eterna.