I had developed a bank of characters for Gett, that served them in all their visual needs. The characters were meant to look very distinct to the brand, in a range from hip and young to business-y looking on-the-go people. I used a thick line with rounded edges - to give it a slick look, and various patterns, to create a rich visual experience while working in monochrome. Also they needed to be built in a way for other designers and illustrators to be able to work with them easily.
I had been working with these characters for four years and I feel like they do not become obsolete. yet :)