The Return of Sol in River of Fire Theory by Grassclaw

Imagine if you will, an alternate end of the Po3 and Oots.
Instead of being petty and trying to get back at ShadowClan for kicking him out, Sol actually does something intelligent. (And in this alternate timeline, Sol has NO backstory, at all. No SkyClan past , no meeting with Midnight the badger)
He tells the 3 the truth of their parents (like they requested) He tells them Leafpool is their mother, and Crowfeather is their father. They are distraught by this, but their new mentor immediately re-assures them that yes, they were born by the breaking of the code, but they were meant to be born, the prophecy proves that.
Time goes on, Sol mentors the three, he helps Jayfeather and Lionblaze hone their powers. Hollyleaf doesn’t reveal the secret at the gathering, because she has a new sense of purpose now.
Sol manipulates the three into believing the prophecy means that they are going to be Leader, Deputy and Medicine cat of ThunderClan, and lead their Clan to greatness.
He’s a puppet master, pulling all the strings.
In Oots, instead of the whole literal dead cats coming back to murder living cats plot, (and the re-use of Tigerstar) we have instead a story of Hollyleaf slowly figuring out she’s not one of the three, and that Dovepaw is.
Hollyleaf is Ivypaw’s mentor in this scenario.
The drought still happens, and Hollyleaf is desperate. She’s already fostered this belief that she is destined to Rule ThunderClan, that it’s her divine calling. She starts manipulating alongside Sol, as they both now realize that Holly really isn’t the third cat. Lionblaze and Dovepaw still go on their journey upriver to defeat the bevers
Together, Hollyleaf and Sol come up with a plan to kill Brambleclaw. (You can either have him die here, or have him blinded or else seriously crippled)
With the deputy position open, Sol convinces Jayfeather to lie to Firestar about an omen.
Jayfeather, believing Sol’s interpretation of the prophecy, convinces Firestar to make Hollyleaf deputy (unaware that Hollyleaf was the one to harm Brambleclaw in the first place)
Lionblaze is surprised that Hollyleaf is deputy when he returns, but is pleased. As far as he knows, this is just fate taking it’s natural course. Completely unaware that Holly and Jay both had a part to play in this.
As Oots goes on Ivypool and Hollyleaf, under the guidance of Sol, start fulfilling their own agendas.
A war between ShadowClan and ThunderClan is started (starting with the battle in Fading Echoes.)
Instead of feeling guilt, Lionblaze is on a power trip of his own. He becomes the main fighting force for ThunderClan.
Hollyleaf, now deputy is trying to get rid of Dovewing without arising suspicions of the Clan, and most importantly, Jayfeather and Lionblaze, who don’t realize yet that Holly isn’t part of the prophecy. Dovewing is forced to flee ThunderClan after Hollyleaf, deputy of her Clan tries to outright kill her. She goes to ShadowClan, because of her friendship with Tigerheart
Sol is pulling all the strings from behind the scenes. He uses Jayfeather and Hollyleaf to start the war with ShadowClan, and soon the whole forest in one huge war. WindClan, who is still hostile towards ThunderClan, becomes ShadowClan’s ally, and there are several battles between ThunderClan, ShadowClan and WindClan, and RiverClan eventually becomes allies with ThunderClan.
In one particularly bloody battle, Lionblaze, on Hollyleaf’s (and by extension, Sol’s) orders kills Blackstar in battle, taking several lives from him one after another. Hollyleaf kills Rowanclaw.
Left leaderless, the ShadowClan cats flee, and join their ally WindClan in WindClan camp.
Firestar wants the war to end, he never meant for ShadowClan to be destroyed like that. But WindClan has sworn vengeance, and the war continues
Sol is beyond pleased by this turn of events.
As time is going on Jayfeather is becoming less and less convinced of Sol’s promises and ideals.
While ThunderClan is still fighting a very real war, Jayfeather turns on Hollyleaf and sets out to discover the truth. He finds out that Dovewing is the true third cat, and that Hollyleaf was the one to either kill or maim Brambleclaw. Sol is upset at loosing one of his most valued pawns. Jayfeather who was once his puppet is now his enemy, just like Blackstar.
There’s an power struggle for control of ThunderClan between Hollyleaf and Jayfeather. Lionblaze feels torn between his sister, who is deputy, and his brother who is medicine cat. Ivypool herself is realizing more and more that what Hollyleaf is doing is wrong. Ivypool joins Jayfeather’s side.
Eventually Jayfeather convinces Lionblaze of the truth. But Lionblaze knows if they continue down their current path, he will be made Deputy when Hollyleaf becomes leader, and he knows with him leading battles, they can eventually destroy WindClan. Hungry for battle, glory, and leadership, Lionblaze decides he doesn’t care if Hollyleaf isn’t part of the prophecy, or that she’s caused harm for personal gain.
In one last final battle against WindClan, Firestar is killed in battle.
Hollyleaf heads for the Moonpool to get her nine lives, but Ivypool ambushes her on her way there. They fight and Ivypool kills her.
Just like ShadowClan before it, ThunderClan has no leader and no deputy.
Jayfeather goes on a peace mission to WindClan and tells them the news. He and Littlecloud come to an agreement, they go to the Moonpool so StarClan can show them who the new leaders will be.
Crowfrost and Ivypool are chosen to be the leaders of ShadowClan and ThunderClan respectively. Both cats go to the Moonpool and receive their nine lives at the same time, with the promise to end the war.

Lionblaze realizes with shame that he could have done more to help his Clan, by putting them first. He failed to act when he had the chance. But he won’t fail again. Alone he meets up with Sol one last time, and puts an end to him. Lionblaze kills Sol and returns home. Ivystar makes Lionblaze deputy.
The three do not loose their powers. Lionblaze and Jayfeather use their powers to keep the damaged ThunderClan safe, while Dovewing uses hers to keep ShadowClan safe.
They were given the power of the stars, and they misused that power. It almost destroyed the clans, but now, the true three work to put things right

Sol would have been the mastermind behind it all, never even lifting a paw, but still in control for a long time.