Ruruko is very loyal to Sona and follows her orders without question. She wants her master to fall in love with Issei Hyoudou so that she could make Saji fall for her.
She has a crush on Saji and has a love rivalry with her senior Momo Hanakai, who is also in love with Saji.
Like Ruruko, Momo also loves Saji and the two have a heated rivalry over him.
Not much is known about Issei and Ruruko relationship, but Ruruko appears to cheer him on to get Sona to fall in love with him so she could date Saji.