Say some one is grappled and failed to save, then is targeted by a dex save spell.

Rules:

No disadvantage on dex saves for grappled condition. The restrained condition does include disadvantage on dex saves.

My opinion:

I agree with rules in that being grappled does restrict you until they lock you down.

Okay so if I grapple a creature and willing walk in to a wall of fire the grappled creature still gets to make his dex save as normal. ???

Just saying cause them not being grappled means they weren't able to escape but they could still avoid a wall of fire even though they being dragged through...

If you're picturing someone grappling you so close that you can't dodge out of the way, then the grappler is also covering enough of you to give you some cover from the spell. That might be one way you could justify how the rules work.

There is a condition that imposes disadvantage on Dex saves, and that's Restrained.

A lot of confusion about Grappled comes from people imagining it to be what Restrained is. Grappled is not a headlock. Grappled is more like I've grabbed your sleeve. You can still move about quite a bit and attack. You just can't move away from me without escaping the grapple.

It's a house rule, but I would allow a second successful grapple check to impose Restrained.

Quote from pavilionaire >>

There is a condition that imposes disadvantage on Dex saves, and that's Restrained.

A lot of confusion about Grappled comes from people imagining it to be what Restrained is. Grappled is not a headlock. Grappled is more like I've grabbed your sleeve. You can still move about quite a bit and attack. You just can't move away from me without escaping the grapple.

 
This is how I see it. I actually use the burly brawl from the second Matrix movie to help me understand this distinction. During the fight, the Smith clones keep randomly grabbing Neo's shoulders, but it doesn't fundamentally impede his mobility, although he needs to get them off before he can move elsewhere. On the other hand, at the end of the fight, Neo is trapped under a whole pile of them, and can't maneuver in his own space.

Quote from pavilionaire >>

It's a house rule, but I would allow a second successful grapple check to impose Restrained.

Interesting. As an action? Replacing an attack? I don't hate this idea.

Yes, as an action.

That is quite literally how the grappled feat works, though it also restrains yourself, which makes sense. 

I understand the concept of it better now. That was a good way of putting it lol.

Thanks every one. Y'all have a good one.

Quote from Aethelwolf >>

That is quite literally how the grappled feat works, though it also restrains yourself, which makes sense. 

 
Right, but the grappler feat is really really lousy.