Fox’s “Fringe” is looking much more mainstream following a hearty week-two performance ignited by the season preem of “House.”

One week after bowing to nothing-special numbers, the high-profile Warner Bros. TV series from J.J. Abrams turned in a much healthier performance as it aired behind one of primetime’s top-rated shows. Surprisingly strong result proves that for all the hoopla surrounding the show’s auspices and heavy off- and on-air promotion, there’s still nothing like a hefty, compatible lead-in to offer a new skein its best chance at attracting an audience.

Future weeks, of course, will reveal if “Fringe” has what it takes to be a reliable long-term player for Fox. The medical/sci-fi skein faces its toughest competish from regular time-period drama “The Mentalist” (CBS) and reality show “Dancing With the Stars” (ABC) beginning next week.

Looking at the Nielsen numbers, “Fringe” (5.1 rating/13 share in adults 18-49, 13.27 million viewers overall) dominated the 9 o’clock hour and improved by 59% in the demo (from 3.2/9) and by 45% in overall audience (from 9.13m) vs. its 95-minute premiere a week earlier.

Fox notes that no new drama on any net since at least 1991 has improved so markedly from week one to week two.

And airing behind “House” (5.6/16 in 18-49, 14.77m), “Fringe” retained 91% of its lead-in among 18-49 and 90% among both 18-34 (4.4/12 vs. 4.9/15) and total viewers. It matched “House” in men 18-49 rating (4.5) and actually built on that rating in men 25-54 (5.3 vs. 5.1).

Yet it gained most in female viewers, spiking a whopping 81% from a 3.2/8 a week ago, when it was asked to kick off the night itself, to a 5.7/14 this week behind “House.”

For its part, “House” was down 28% from last year’s premiere-week bow in its longtime 9 o’clock slot (7.8/19 in 18-49, 18.31m). A sked change, designed in part to boost circulation for “Fringe,” likely kept its numbers down some, since fewer people watch television in the 8 o’clock hour.

Elsewhere Tuesday, NBC’s “The Biggest Loser: Families” got off to a solid start (3.2/9 in 18-49, 7.94m), up a tick vs. its bow a year ago, which faced lighter competish.

At CW, “90210” (1.7/5 in 18-49, 3.29m) was flat week to week in 18-49 but rose 14% in 18-34 (2.4/7 vs. 2.1/6) — a good sign opposite such drama competish as “House.” “90210” continues to struggle to attract teens, however, logging just a 4 share in that audience.

Airing behind “90210,” fellow frosh “Privileged” (1.1/3 in 18-49, 2.43m) was off a bit from its premiere in most categories but retained all of its opening-night 18-34 aud (2.4/7).

And CBS’ “Big Brother” wrapped with this cycle’s best scores (2.7/7 in 18-49, 7.56m).