First of all, try adopting or visiting a reputable breeder! A reputable rescue or breeder will help you find the perfect friend for Daisy and will help you with introductions. It's a very rare rat that is unsocial, especially after such a short time alone. All of my personal rats came from Craigslist, and had lived alone their entire lives, and they very quickly learned the joys of a big snuggly rat pile and having boxing matches with their siblings.
We are as gods to the beasts of the fields. We order the time o' their birth and the time o' their death. Between times, we ha' a duty. - Terry Pratchett.
"Men have forgotten this truth", said the fox, "But you must not forget it. You become responsible, forever, for what you have tamed. - Antoine de Saint-Exupéry