The loosehead prop has made the move to Saints from Harlequins, even though the 2020/21 season has yet to finish.
Auterac, like so many players in England's top flight, has found himself switching clubs during what is almost the middle of the campaign due to the Covid-19 pandemic.
The season was put on hold in March and because players have signed contracts at new clubs from July 1, those commitments have been honoured.
It means Auterac has started the campaign as a Quins player but will finish it with Saints if, as planned, the Premiership resumes in August.
It's a strange feeling for the 27-year-old, who has already sampled some stand-out Saints-related career moments.
Auterac explained: "I've played quite a few times against Northampton and it was always a tough place to go.
"I remember that I was 24th man when I was at Sarries and Saints won the Premiership final back in 2014. That was a memorable game.
"I wasn't in the matchday squad but I was down there and did warm up.
"I had come through the whole Academy system and it was my last match at Sarries before moving to Bath.
"I was upset for the boys who were playing but it was a good little taster to watch that.
"Sarries had been hoping to win and I just remember how upset everyone was.
"I also watched the game the week before when Saints won against Bath (in the Challenge Cup final) because I was going to Bath.
"Also, I made my first-team debut against Northampton in an LV= Cup game in 2011.
"As a first-year prop I didn't think they'd really want to put me on against the players that Saints had out there that day. They had Soane Tonga'uiha, Dylan Hartley, Brian Mujati and Paul Doran-Jones.
"Deon Carstens got a bit tired towards the end of the game and wasn't really fancying the LV= Cup much so he came off and I got to have a 15-minute runaround at the end of the game."
So how does Auterac feel about now being a Saints player and what is it like to swap life at seventh-placed Quins for Chris Boyd's fourth-placed side?
"It is a tight league and you can jump between second and ninth quite quickly," he said.
"There are a lot of teams bouncing about and you can be in the top four one week and loving life but then drop down and have panic meetings.
"But Saints have been in the top four all year and so when we heard players would go to their new clubs now I was quite looking forward to that.
"I thought it would be quite cool to play less than half the season and potentially win the title and imagine winning in Europe as well!"
Having come through the ranks at Saracens, Auterac made the move to Bath in 2014 and played a key role as they reached the Premiership final in 2015.
But things didn't work out so well at The Rec in the end, with Auterac saying in an interview a couple of years ago that 'things turned to s**t towards the end at Bath and I just couldn’t recover from perceptions the coaches had of me'.
He ended up at Quins and it seems St Albans-based Auterac feels he has matured a lot in the past few years, giving him the perfect physical and mental platform to build on at Saints.
"Ever since about the age of 16, it was an uphill progression and things were going well for me," Auterac explained.
"When you get in a flow of improving and improving and things going well for you, it's easy to stay in that routine.
"But when I was about 23/24, it was probably the first time since I started playing rugby that things hadn't gone well for me.
"I didn't really know why it was and I didn't know how to react to it because I was used to things going well for me.
"All you have to be is one or two per cent off and that's when things go wrong.
"You always have to be at the top of your game. You have to be recovering to make sure you're the best player you can be at the weekend, but I got into a bit of a rut and didn't really know what was going on.
"Whether I blamed it on external things wrongfully thinking it wasn't my doing, I wasn't playing that well and it's taken a couple of years to mature and realise it's all my own doing how my career has panned out.
"Fortunately I've come to realise it with plenty of time left in my career.
"Now I've got the opportunity to come to a good club in Northampton and I can use everything I've learned, the ups and downs, in my career so far to help me kick on again and do well within the team and for me personally."
On that spell at Bath, which started to fall apart when Todd Blackadder arrived, Auterac said: "I got on well with the coaches when I joined but then some new coaches came in.
"All coaches are different and you have to adapt to them and understand what they want from you as a player.
"I didn't adapt to what they wanted from me and didn't learn how best to deal with them.
"I was like 'I want the old coaches back, I was happy to deal with them' but that was probably quite an immature way of looking at it.
"Now I can appreciate that you've got to go out of your way to understand the coaches and what they want.
"That will get the best out of you and the team.
"That's why when Boydy and Matt Ferguson wanted to sign me, I got quite excited because they were coaches who'd liked what they'd seen.
"We'll do what we can to get the best out of each other and I've been really looking forward to getting back into it."
Auterac's early enthusiasm for life at Saints is clear.
And he added: "It's been good so far.
"Obviously it's been different to going to a new club in any previous year, but I've enjoyed it.
"It's been a long time coming and I just wanted to get back into the swing of rugby again.
"It's early days and I haven't met too many people but I've felt very welcome coming here.
"There has been continual communication about coming here and from the coaches to Paul Shields, they've been looking forward to me coming and I've been looking forward to it, too.
"I found out I'd be coming here last autumn. My agent mentioned Saints were looking at me and I was like 'oh, class'.
"I'd seen how well they'd been doing and I wanted to meet them. I had a meeting with Boydy, Matt Ferguson, Phil Dowson and Paul Shields and it went from there."
Auterac and Saints have almost mirrored each other, enjoying superb progression up until 2015, which was the year the black, green and gold finished top of the Premiership regular-season standings and Auterac helped Bath into the final.
They have both had some tough times since, but both parties will now aim to continue their revival together, with Kiwi boss Boyd the catalyst at the Gardens.
"I didn't really take too much notice of them (Saints) until we played against them at The Stoop last year," Auterac said.
"Before that, Saints hadn't been doing too well and were in mid-table. You only really notice what's going on at the top and bottom of the league.
"But then we played against Saints in that game after Boydy came in and I thought Saints (who won the game 20-19) are actually quite good.
"They attacked us and I really started taking notice of Saints again.
"Then Saints beat Sarries in the first game of this season and I spoke to my friend at Sarries and he was like 'yeah, Saints are actually a really good team'.
"Historically they used to run riot with that front row of Tonga'uiha, Hartley and Mujati but now there's an emphasis on flowing rugby.
"But there's still this prowess at Northampton with them having a big, strong pack and I'm looking to being involved with that."