Snowbarrisco

Snowbarrisco is the poly ship between Barry Allen, Caitlin Snow and Cisco Ramon from the The Flash fandom.

Canon
Cisco met Caitlin and her then-boyfriend Ronnie when he became an employee of the same company that employed S.T.A.R. labs. Over time, they became friends and developed a brother-sister relationship.

The labs created a particle accelerator whose explosion killed Ronnie and put Barry Allen a CSI into a coma. who was later admitted to S.T.A.R. Labs where Caitlin and Cisco continued to work. Upon awakening Barry discovered that he had gained super speed and that the explosion had also given the powers to other people who, however, used them badly. Eventually Barry decided to use his powers to stop them and find out who killed his mother and so Caitlin and Cisco became his support team.

Fanon
This ship is very popular. Barry, Caitlin and Cisco are seen as the hard core of Team Flash and many fans have not approved that from the second season onwards, with the flooding of Team Flash, the three have begun to have fewer moments together.

Fan Fiction
Barry/Caitlin/Cisco on Fanfiction.net