are cats with both red and blue in their coats always chimeras?
Basically yes, usually.
Blue is dilute and red is non-dilute, this combination cannot naturally occur in a single individual… unless something crazy happens, like chimerism.
There may be other genetic anomalies that result in the same or a similar effect but I’m not well-versed in them and couldn’t tell you what they are or how common they are.
There’s also “red-blue tabbies” which aren’t chimeras but their own thing and can vary from actually looking red-and-blue to just looking kinda dirty gray-orange.
There are also normal color patterns which can look deceptively like red-blue without actually being the real deal due to influences from things like rufousing.



















