Leafpool was a medicine cat. Medicine cats are forbidden to have kits, so Leafpool gave them to Squirrelflight instead. Leafpool used parsley, a kind of herb, to stop her milk flow.
Hope this helps!
Brambleclaw thought the kits were his because Squirrelflight passed them off as his to protect their true parentage, which was revealed later to be Leafpool and Crowfeather's kits. Squirrelflight did this to protect her sister, Leafpool, who had broken the warrior code by falling in love with Crowfeather.
No they don't have any kits. You may think that they did have Jaykit, Hollykit, and Lionkit but those are actually Crowfeather and Leafpool's kits. Squirrelflight covered for Leafpool and took the kits.
Brambleclaw has no kits biologically, since it has been revealed that Squirrelflight did not bear him kits; instead, the kits were her sister Leafpool's. However, his adopted kits (the aforementioned kits) would be Jayfeather, Lionblaze, and Hollyleaf (presumed deceased).
Leafpool; his father was Crowfeather. For a while, though, Leafpool and Squirrelflight lied to the clan and told them that Jayfeather and his two siblings were Squirrelflight and Brambleclaw's kits.
Yes they will but they do not have kits. Brambleclaw thinks Squirrelflight has Hollykit, Jaykit, and Lionkit but Squirrelflight was just keeping a secret for her sister, Leafpool. Those kits are actually Leafpool and Crowfeather's kits. Leafpool is the medicine cat so she is not allowed to have kits but she did.
He never meant to kill Hawkfrost, he accidentally impaled his throat while trying to save Firestar. Later, he realized, Hawkfrost would have been very dangerous to the Clans. He also killed him because Hawkfrost was trying to kill Firestar (Brambleclaw's former mentor and current leader).
Because Leafpool is suspicous of Hawkfrost and Brambleclaw is spending a LOT of time with Hawkfrost and, of course!, Squirrelflight sides with her sister, and Brambleclaw won't refrain from seeing his half-bro.
Their kits where believed to be jaykit/paw/feather hollykit/paw/leaf and lionkit/paw/blaze, but they are really leafpool and crowfeathers kits. Squirrelflight lied and told the clan that they where her kits and not leafpools because the kits were half clan and leafpool was a medicine cat. But hollyleaf died when the tunnels collapsed while she was trying to run away from her clan to start a new life. Squirrelflight tells Ashfur that hollleaf,jayfeather,and lionblaze are not her kits because Ashfur was going to let them burn in a forest fire because he once loved Squirrelflight but she chose Brambleclaw over him so he said to her letting her kits die would hurt her in away.Then Squirrelflight tells Ashfur that they are not her kits and he wont hurt her by killing them. Later you find out that jayfeather and lionblaze are really Leafpools and Crowfeather of Wind Clan kits. Squirrelflight and Leafpool lied to protect Leafpools kits and Squirrelflight told everone that they where Squirrelflights and Brambleclaws kits. In Sunrise Leafpool resigns as medicine cat leaving jayfeather as a full medicine cat and Leafpool as a warrior.
they didn't squirrelflight lied.
No, SqurrielFlight and BrambleClaw never has kits, but SqurrielFlight takes care of her sister, LeafPool's, Kits; HollyKit, LionKit, and JayKit, Because LeafPool was a medicine cat when she had her kits in the forest with CrowFeather of WindClan.
Because when Hollyleaf revealed that she and her littermates (Jayfeather and Lionblaze) were halfClan by being Crowfeather of WindClan and Leafpool's kits, Brambleclaw was outraged in Squirrelflight for lying to him and not trusting him enough as a mate to keep Leafpool's secret. He never forgave Squirrelflight for her disloyalty and didn't think of her as a loved one, only a lowly Clanmate who had been lying to him for moons.
Squirrelflight was foster mother to Jayfeather, Lionblaze, and Hollyleaf, but as revealed in Sunrise, they are actually the kits of Leafpool and Crowfeather. I suppose Squirrelflight is barren because she had been mates with Brambleclaw for so long and still doesn't have kits. But since they are not mates anymore, Squirrelflight probably won't have any kits.