'Chicago P.D.' season 4 spoilers, plot news: Jesse Lee Soffer talks 'Linstead' moving in together; Voight-Lindsay relationship to have 'seismic change'

Lindsay (Sophia Bush) and Halstead (Jesse Lee Soffer) are taking their relationship to a new level, now that they will be moving in together in "Chicago P.D." season 4.

 After ending her relationship with Lieutenant Kelly Severide from "Chicago Fire," Lindsay had since grown closer to her partner on the force, Halstead. Wednesday's premiere saw Halstead finally asking his girlfriend to move in with him, and Lindsay was not able to refuse his romantic declaration.

According to Soffer, fans should look forward to how the dynamic between "Linstead" will change and if the relationship will still work as the begin living together. "...To this point, they're partners, and they got each other's backs, and they enjoy the relationship when it's convenient for them, and this is taking a big step forward, he told Entertainment Weekly. "It'll be interesting for the writers and for us, as the actors, to play out where that goes."

Meanwhile, the season 4 premiere also saw Lindsay covering for Voight (Jason Beghe) at the expense of her own career. With Commander Crowley (Barbara Eve Harris) breathing down her neck about her boss' act of vengeance, Lindsay did the unthinkable and helped Voight get rid of any evidence that would implicate her pseudo-father.

After the events of last season, Lindsay and Voight's relationship will certainly change in a huge way. Now that Lindsay's debt towards Voight for saving her life has been paid after she helped clear his name, she will be spending more time with Halstead instead of worrying about her mentor.

"... This is what we're playing right now, this kind of seismic shift in the relationship between Lindsay, Voight, and by extension, Halstead," showrunner Matt Olmstead told TV Guide. "Voight does articulate to Lindsay, 'You're all I have left.' And he's carrying that, too, seeing someone kind of leave the nest who's also the last loved one [he has] out there."

The fourth season of "Chicago P.D." airs Wednesday nights at 10 p.m. EST on NBC.