Codsworth:

He claims a bit of change of pace and focusing on something besides always combat is good and he will be here to help if you need it. So when you need help lifting stuff he's quick to grab and help. One time he tried to grab something way too heavy and broke one of his arms so you had to spend the time trying to fix it, for which he apologized, somehow sounding embarrassed this happened. Once fixed again he decided to focus on the lighter stuff and do the boring clean up stuff so you can focus on changing everything and fixing stuff.

Preston:

He loves it, and hopes you will also fix some more buildings for other people. He gladly helps you out, and if it's a big job then he will call over some others to help out as well. He makes sure to keep all the supplies you throw out as one never knows when they can use the extra stuff. If you throw out a desk he will be sure to place it in a house without one. Seeing it go from a terrible, torn down house go to a great, clean, proper house it brings such joy and hope to him, and he uses it to encourage others to do the same to their houses and start influencing others to do it as well to create a better, cleaner, more hopeful future.

Danse:

He lifts all the heavy stuff, each time asking where you need this then walking to where you point or say. He will pull stuff off the wall, like the wood off boarded up windows. When he has nothing to do he just rests, checks the supplies, makes you some food, or keeps guard outside for any potential danger. When you get tired from all the work he gives you a hug from behind, giving a kiss to your temple, telling you you are doing great so should reward yourself with a break.

Piper:

She makes a report about it, trying to make it sound as good, easy, and fun as she can to influence others to also do it as she finds this a fantastic idea and always thought people should stop letting the world be this shitty. She finds it stupid people haven't started doing this yet, complaining that it has been 200 years so everyone had enough time to process, grief, and start rebuilding. She posted the report but not much changed. But once you finished your work she did it again and then it did work, probably as it was seen how easily and quick it indeed was. She did help with a few tasks, mostly small, but she was more focused on spreading the word and influence as she wants to fix the shitty way the world is now and she had tunnel vision to how this might be a way to fix it.

Nick:

He finds it great and will visit, even help but that's usually only if he doesn't have cases to solve. He praises you, making sure you still eat and drink enough, help you with the annoying tasks, all such things to ensure you keep motivated to do this till the end since this is a great idea. When you need a break he will ask if you need anything or if he should continue the work. When he arrives and sees you being tired he gives you a hug, advising you to go take a nap while already walking you to your bed.

Hancock:

He found it great. It's what he did with Goodneighbor so he helped out, and people in Goodneighbor also gladly helped out. Sometimes he just lays back, takes some stuff, and watches you working. It's weirdly relaxing, fun, and sexy to watch you cleaning/repairing. When you scolded him to help out or otherwise get lost he just hums, totally not properly processing with all the stuff swirling in his system, so you just end up letting him lay there and get back to work. Once it's done he gives you a big proud kiss, praising you then thanking the others for helping out as well. If everyone had fun, it didn't go too bad, and have enough materials and time he excitedly proposed to everyone they do this to more places.

Cait:

She found it a waste of time, telling you every place is shitty so just blend in. It caused a lot of dumb arguments, but eventually it was settled when you shouted "just let me have my fun!" so she left you to have your fun. She just did some scavenging, annoyed at you for wasting time with what you are doing but still making sure to get a lot of food and water for you. Once it was done she was impressed with how new the place looked, as if right before the nukes fell, but of course refused to admit how impressed she is and just gave a cool "yeah, it's good" with a shrug.

Strong:

He finds it boring, claiming he wants to go smash things. So you keep him busy by making him move around the heavy stuff or sending him to go kill enemies that get too close. At one point he tried to help with the delicate and small stuff, but ended up breaking it all so you kicked him out. When you returned to check on him a few hours later he was sitting outside, sulking while smacking his melee weapon on the ground, muttering about how he only wanted to help. So you put him back to work, making up a lot of fake issues that need his attention. Once it was done he was even proud about what you two did, and even brags about it to others.

Maccready:

He found it nice and relaxing, though it made him feel a bit somber and sorrow as it makes him think of his wife and kid and what life they could have led. He likes doing this with you, but his mind just wanders so he works harder to try and keep his mind on the tasks at mind and not wander. When you start overworking he worriedly pulls you away from the work, telling you to go take a break and nap or eat something. It was a weird time as it didn't feel as if the apocalypse ever happened, especially when it was fixed and almost looked how it originally did. So leaving this place is extra shitty as it reminds him of how reality really is and the circumstances ever is stuck in.

Deacon:

He was a bit confused but wanted to help out. It's also fun to have something with a goal that can be achieved quick as it passes the boring hours, makes one feel hopeful, and is just nice to do something with you. As he cleaned out the stuff he had a cringe the whole time, not liking touching all this old stuff. He tried to keep it silly and playful to avoid this being a serious, boring, frustrating thing. Once it was done were both so proud and he gave you many high fives and kisses; so excited and proud you two did this.

Curie:

She helps you out if you ask. She enjoys painting so if you need anything painted can just give her the paint and brush then leave to go do some other task. When she has nothing to help with she starts making you meals to ensure you still eat. If you refuse she forces you to sit down and pushes the food in your hands, scolding you you won't be able to do anything if you do not replenish your energy and take a break. She stays standing there, watching until every bite is gone and you have rested for a few minutes, then she lets you get back to it.

X6-88:

He found it a waste of time yet also good, mostly for your own mental health as it helps you forget about your worries a bit. But if you put all your time and energy into it after a while he will remind you of other things you still have to do, especially to the Institute. He isn't around a lot during this time, mostly pops in to see how you are doing or lend some help with lifting heavy things and dangerous tasks. Once it was done he even felt weirdly proud of it, or at least that's the best he could explain it as. He congratuled you then asked if you are ready to do your other tasks now.

Dogmeat:

He kept running around the whole time; to either play or bring you supplies. He even tried to drag the wooden planks to you. It was handy so you could just tell him the supply tool and somehow he always brought the right one. He didn't mind helping, especially when you pet and/or praised him each time he helped out.

King:

If you decide to fix up Freeside he has the Kings help you out, not that he had to really order them because they were all excited to start fixing things around here, and most also were just bored with the same typical patrolling and hanging around. He makes sure you have all supplies and usually comes by to see how it's going and gives some praise that it's going good and he's excited to see the end result.

Benny:

He finds it great you clean up places as it gets more people. The repairing part he doesn't get to. It's all been fine enough so why bother repairing; is his mindset to it. But if you really desire to do it he will lend you the caps for the materials. Behind the Tops was all the materials they threw out when this place got fixed up so he lets you use whatever you need from there to fix up another place. If you do a good enough job and clean up many places until it doesn't look how it used to then New Vegas even becomes known as a literal new place, where you feel as if the nukes never even fell.

Butch:

He didn't see the point; he found it a waste of time. He has gotten used to all the broken buildings so he didn't care to fix it, but then you began asking if he wouldn't like to have a proper place to stay in and not a gust of wind or rain always waking him up. That made him sigh but start helping as he would like to have a place to finally stay without complaints. He was so excited and proud when it was done, almost jumping on you as he cheered you two did this and this is dope.