Required npc summons?

[Zan]

I'm doing my second playthrough and was planning on following as many quest lines as possible and I know that some require them to be summoned against certain bosses. Which npc's and for which bosses need to be summoned to progress there story line? Thanks in advance

[Watermelons]

None are truly required to be summoned to continue a questline.
For Sirris of the Sunless Realms, she actually summons you twice. You find her sign and then join her world. You can help her on the bridge in Irithyll and at the Pit of Hollows in the Undead Settlement, outside of where the Curse Rotted Greatwood boss was. Once you do that, and you complete I believe the Twin Princes boss fight, she will die and leave her Sunless Talisman and the Sunset Shield on her grandfather's grave outside Firelink

For Anri, she summons you to help her fight Aldrich. As long as you saved her from the Chameleon'd Pilgrim servant of Yuria. Helping her beat Aldrich will have her leave her sword in Firelink with Ludleth.

For Yuria, if you go down her road, she will leave her clothes and sword behind in Firelink if you summon her for the Soul of Cinder fight, and she survives.

I guess it counts, though it's not summoning, but if you help Siegward of Catarina in all his three predicaments ( slaying the Demon in the Undead Settlement, getting his armor back from Patches and helping him out of the well in the Cathedral of the Deep, meeting him in the kitchen in Irithyll then rescuing him from the cell in the Profaned Capital) then he will join you for the fight against Yhorm the Giant. Once that fight is over, he'll do another toast and take a nap. Once you turn around and make enough distance, he dies, leaving his armor, shield, and a spare Storm Ruler

Hawkwood the Deserter can be summoned in Archdragon Peak, and he'll accompany you until you sit and pray at the giant Dragon on the mountain. Once you get the Twinkling Dragon Stone, he'll leave. It's not necessary for him to be there though. Once you get that Stone, he'll leave a note with Andrei the Blacksmith, and you can meet him in the Abyss Watcher room to fight him

[Herbalacious]

Just look em up on the wiki it's faster than re-typing it all here.

Sirris and Greirat are prolly the only 2 npc's that are easy to messup the questline.

You can turn in Orbek's Ashes to Yuria after Orbek's questline is complete without actually killing him.

Yuria can be summoned for the Soul of Cinder fight and will drop Darkdrift where she usually stands in Firelink

Pale Shade set can only be obtained if you kill him in Irithyll. (Failing Yuria's questline required before killing Pontiff)

There are npc summons that give you Gestures if you summon them. Heysel, Pale Shade, Black Hand Gotthard, and Knight Slayer Torig all reward the player with gestures. I may have missed one or two I don't remember atm.

[Zan]

Ahh, thanks for the quick response :) What area do you need to save Anri from the Chameleon'd Pilgrim servant of Yuria?

[Herbalacious]

GameZorg の投稿を引用：

Ahh, thanks for the quick response :) What area do you need to save Anri from the Chameleon'd Pilgrim servant of Yuria?

Irithyll, but it requires failling Yuria's questline and will continue with Anri's from there.

[Zan]

The questlines are so confusing haha

[MOSLEY]

GameZorg の投稿を引用：

The questlines are so confusing haha

That's kinda the point. You're supposed to spend a few NG cycles figuring them out. :)