Zuhair ibn Qayn was known soldier of Husayn, which as it was reported was martyred along with Husayn (radi Allahu anhu) in Karbala.
Let us see what history book (p 5) says about him
Translation:
“Zuhayr believed that Uthman ibn Affan was killed wrongly, and due to that it is known that he was inclined toward (being) Uthmani and (his) desire”
gift2shias.com 
Hmmm very informative…And we all know it is proven from both Shia/Sunni historian the both Hassan and Hussain(May Allah be pleased with them both) were guarding Syedana Usman bin Affan(r.a) against the mutants.Allahumdallah truth prevails always.