We'll give you a ride with 〜てあげる
Grammar Explanation: Doing for someone with 〜てあげる

Hakumei and Mikochi search for a specific café to no avail. A couple of rodents come up from nearby water.
- ネズミⒶ:
- 「私ら場所
( 知( ってるからさ」- “We know where it is, so...”
- ネズミⒷ:
- 「乗
( せてってあげるよ」- “We'll give you a ride.”
Key Points
乗
( せていってあげる = “we’ll take you there”乗
( せる means “to let someone ride”.〜ていく adds movement away, toward the destination (the café).
Casual contraction: 乗
( せてって乗
( せてって is the spoken contraction of 乗( せていって.The small っ marks the clipped sound in casual speech, so the written form matches how the offer is said aloud.
Why 〜てあげる fits this offer
〜てあげる means doing something for someone else’s benefit; the rodents are the ones kindly doing the taking.