Hawkfrost knew that his father was Tigerstar because Sasha told him and Mothpaw(wing) that Tigerstar was their father. And then Tigerstar probably just started to visit Hawkfrost and that is how he turned out to be so evil.
In the Warriors series, Sasha is not Hawkfrost's mother. Tigerstar is his father, and they communicated through dreams and Firestar's StarClan visit before Hawkfrost's death in the "Power of Three" series. This allowed Tigerstar to influence Hawkfrost's decisions and actions.
Tigerstar wanted Hawkfrost to lead RiverClan and Shadowclan combine and Brambleclaw to lead Thunderclan and Windclan combined. Obviously this was never fulfilled: Hawkfrost is dead, and Brambleclaw is just an ambitiously loyal deputy of Thunderclan.
Rogue RiverClan
Tigerstar first has kits with Goldonflower when he was in Thunderclan.Before the kits where born he left Thunderclan.The kits names where Brambleclaw and Tawnypelt.Then in Shadowclan he has kits with a loner Sasha. Before they where born he got killed. Somehow the kits got to Riverclan and they where named Hawkfrost and Mothwing.
Hawkfrost becomes deputy of RiverClan after Mistyfoot goes missing.Hawkfrost is a blood and power thirtsy cat. He is the son of Tigerstar and Sasha(a rouge). He had a brother: Tadpole before his mother Sasha took him to riverClan. Tadpole dies when he was a kit from drowning. Hawkfrost has a sister named Mothwing who was a medicine cat and two half-siblings named Brambleclaw and tawnypelt.
Yes, Hawkfrost has one daughter named Mothwing. She is a RiverClan medicine cat who initially pretended to receive prophecies from StarClan. Hawkfrost mentored her briefly before his death.
Sorry there is no Hawkhead is the warriors series, there is Hawkfrost (Brambleclaw's half-brother and Mothwing's of Riverclan brother.)
Firestar, Graystripe, and Ravenpaw diverted the attention of the RiverClan cats, creating a distraction that allowed Mistyfoot, Feathertail, and Stormfur to escape unnoticed. They used their knowledge of the forest and their fighting skills to provide cover for the fleeing cats, ensuring their safe escape from RiverClan's camp.
Tornear of WindClan. Heavystep, Swallowtail and Stonestream of RiverClan.
Leopardstar of RiverClan had three known apprentices: Hawkfrost, Mistyfoot, and Stonefur. Each of them became skilled warriors under her guidance.
I the previous books you know when Lionblaze was an apprentice that he goes in the underground tunnels with Heatherpaw. No Lionblaze is loyal to his clan and will not mate with a riverclan cat.
The rebellion was led by Mudclaw. The members of the rebellion are... 1. Webfoot of WindClan 2. Nightcloud of WindClan 3. Hawkfrost of RiverClan 4. Blackclaw of RiverClan 5. Cedarheart of ShadowClan 6. Two unknown ShadowClan warriors
The sick cat in RiverClan in "The Fourth Apprentice" series is Mosspelt. She is suffering from a cough due to being exposed to contaminated water and is quarantined from the rest of the Clan to prevent the spread of illness.