Why the Pacifier?

I went through this too. The older one was 3 at the time. It is definitely an attention seeking action. Most of the time I would say, "be a good big brother and give it back" or involve him in the care of the baby and ask "can you find me a paci for baby?"
It worked out really well and when he said he didn't want to I stayed as unemotional as possible and said "okay maybe you'll feel like helping later."

Only ask him once and then swoop in with another one if he doesn't comply. Try to not fuss over the baby when you do it either. I know it's hard not to gush over the baby every second, if you do, try to take and equal time to gush over the older child.

I did this with a brother sister team I cared for and my niece and nephew who were about the same age apart as your two. It worked out well both times.

My opinion is he is doing it for attention. My daughter was 18 months old when my son was born and she didn't bother his pacifier but she wanted his bottle, not to drink but to pretend she was the baby. They seem to do whatever they can to get the attention on them and off the new baby. I would say give it to him and see what happens. Also, try spending some alone time with just him during the day and give him lots of attention. Tell him what a great big brother he is and point out all the things he can do that the new baby can't. My in-laws bought my daughter a book called I'm a Big Sister by Joanna Cole and Maxie Chambliss and it helped a lot. They also have a book called I'm a Big Brother and you can find it at Barnes and Noble for sure. Maybe something like that would help too.

Get rid of the pacifier in general. I have never used it and my two beautiful daughters have gotten along without it just fine. That will prevent any further problems of jealousy with the oldest.

First of all, it is completely natural for an older sibling, especially one that is still a little one himself, to regress and do some baby-ish things when a sibling comes along. Some kids want to use bottles, some refuse to use the toilet and want diapers again, some want to be carried all the time, etc.

It sounds like Asher is doing some regression. You could just give in and let him have binkies if you don't want to fight it, but get the bigger ones for him. This might even take away the "forbidden fruit" aspect of it, and he might decide he really isn't that interested. But most likely, you want to keep him bink-free, so you might need some other tricks.

You could get him a cool sippy cup that he absolutely loves and take it away from him when he takes the bink. You could emphasize how binks are for babies and he is big although this might backfire and make him want to be more of a baby in your eyes, so you need to decide if this is the best approach for his personality and stage of development.

You could also do a sticker chart. He might be a little young to understand this so it would need to be very simple. Like each evening if he hasn't messed with the binks, he could put a sticker on a chart. When he got three stickers or so, he could pull a little toy out of a treasure chest. You could also have a toy box with some special things in it that he could only play with during the key times when the baby is hanging out sucking on the bink.

It is an amazingly tough time for the older sibling, especially since he is still somewhat of a baby himself, so just be patient with him and give him the support he needs to be a great big brother.

Other than hiding them, I'm not sure there's much you can do when your oldest is this young. I don't think he's doing it for a reaction, but he might remember that he used to have one that looked just like this one that the baby is using.

Or maybe you could let him have it and see if the novelty wears off. Can you do that w/o him having to have it all the time while sleeping?

My children are all close together like that, and we had the same issues. With my first two, I hadn't tried to take it away, so they both came off it at the same time. The way I have done it since then is to literally hide the pacifier. When the baby is in the car seat, put it under his butt or something (I hide it under the little head holder thing). When he is in the crib put it under a blanket. If the older one doesn't see it, then he probably won't think about it. Of course, you can't hide it when the baby actually is using it, but for me, it has always worked to just say,"Oh, thank you" while I just take it away. OR, the best thing (this works better with girls, but it will work with boys, too.) is to let the older one help. If you say,"Thank you for helping with your brother! What a big boy! Ok, now put it in his mouth (or in his seat or wherever you want it.)" When the little ones think they are helping they are much better about it. My daughter is at that age and I have a newborn, and this ALWAYS works with her. Now she is always trying to "help", and his paci ends up in his eye or something, so watch out for that when the baby is in reach!!!