So I've been working this theory since vanilla destiny 2 and as more and more comes out about forsaken. I'm going to say it again. The simple version. Zavala as of the end of the vanilla story is being unknowingly controlled by savathun. Now i don't think it a case of full control but she is manipulating his action. Now everytime i mention this i get flak. I never get a valid 'it can't be cause....' it just it it can't. So I'm going to speak as much of how i see things. So where did this begin. When did she get her string on zavala. And I say it start on titan. Now going to titan in then immediate event of losing there light. Now we know its cause of the AI core. But when you hit dug in hive. Rather than pulling back and finding a secure place to fall back to. He kept ordering attacks to get the AI core. And when our guardian shows up rather than being pumped we have light he's depressed almost. It sloane who acts to make the most of what to them is a miracle.  Then zavala seems out of sync. Which yes could be him still struggling with the lost of his light but sloane isn't broken or holiday. There both focused. So we get the Ai core. Decode the messages and we learn of the almighty. A ship capable of destroying the sun. So zavala plans to attack and destroy it. Nothing weird but as we learn due to ashir mir sudden assistance on Io. Destroying it would kill us all. Now maybe zavala is still not all there or maybe he didn't understand we he was reading. But then again what if he did. Sava seeing everything. Understanding everything. Playing on zavala anger. Attack the almighty. Nova the sun and then she takes the dreadnought. It survive the harbinger. A super nova would likely not destroy it. If asher hadn't decide to reveal himself. We might of never knew the extent of threat we were in. After that. We get the traveller back the next thing is the sava song strike. This takes a bit of thinking outside the box. We were sent in after a trio of fireteams went missing. Now they were sent down due to a weird hive ritual. But as we see the amount of crystals. More than 9 guardians lost there void light. Zavala only finally get involved after 9 are lost at once. You must think any operation where 9 guardians are dispatched would need signing off by the vanguard and as sloane been over seeing everything it likely means zavala signed it off. Now i've argued why did the vanguard seek to hold titan. If the hive are so dug in under the water. Why not just sink everything. Drown the hive in liquid methane. What is on titan the vanguard needs. Nothing as far as i can think but if zavala is being whispered to by sava. Made to believe there is something there. Now when our team get there and we reach the final chamber we find the shrieker. Who to say it was just made? It could of been there since oryx fell. Watching and zavala sending us down to kill it could of been sava having zavala act to make it seem he was still acting for the vanguard and removing a tool she no longer needs. So there nothing else in vanilla d2. But warmind. The simple fact zavala is on mars. I had someone argue that it was an all coms sos ana sent out. Which is fine but zavala is the vanguard commander. Think about this from a real life army. When an sos is sent out and other forces are in route would the leader of that force go alone to answer it. No. But them zavala is there trying to stop as getting to Rasputin. And he happens to know exactly who we are fighting. Xol and nokris. Xol would be in the hive bible but we know nokris was erased. So how does he know that? Eris and asher found nothing but Zavala knew. And we know Nokris force were calling to sava. Nokris calling to his Aunt. Now we 'kill' Nokris and Xol. We awaken Rasputin and he set out to defend the galaxy. We know ana trust him. And yes we should likely be a little on edge considering. But zavala is horrified. Again a miracle in Rasputin setting out to defend. Another miracle that zavala isn't happy about. Now there might be something i've missed in the lore that burn this all down. But we known sava is a manipulator. She manipulated oryx her brother and she ended up more powerful. She did is to her nephew Crota making him slice into vex realm. Now we have talk uldren hearing a voice from the dreaming city which is driving him down his current path. Now it could be sava, could be mara. Could be someone new. But if it sava and she can do it to someone like uldren. Who to say she couldn't do it to a lightless and broken zavala. This is all theory. I have little to no hard lore to support any of this. And any lore to support or disprove is welcome. But until i get some lore that makes this theory impossible. I will keep digging and adding to it.