Of all the fathers-in-law in the Bible, only two are singled out as such.
The first is Yitro, who is contrasted to Lavan. Just as there are no two more similar stories than the respective exiles of Yaakov and Moshe, it is hard to find two more disparate parallels than the roles of their respective fathers-in-law. Whereas Lavan does something disagreeable at every turn, Yitro does just the opposite, constantly providing help and support to Moshe. Moreover, in place of the resentment Lavan shows his son-in-law, Yitro shows respect for his son-in-law’s independence – a respect that is likely the most vital element in such a relationship. The Torah emphasizes the difference by constantly referring to Yitro as Moshe’s father-in-law, while Yaakov’s father-in-law, Lavan, is not described as such even once.
The second is the anonymous father of the concubine of Giv’ah (Shoftim 19:1-10). That father-in-law is also notably benevolent in his treatment of his daughter’s husband. Specifically, he rejoices when he sees his son-in-law, feeds him, beseeches him to prolong his visit and, ominously, not to leave when it is unsafe. And, like Yitro, he allows his son-in-law to make his own decisions.
This arrangement of equals is the only one a son-in-law can comfortably accept from someone who is ultimately a stranger. Treating strangers as equals (even when they are not) requires far-sightedness and the understanding that when strangers work together, it usually benefits everyone. This, despite the loss of status or property that it might originally entail. It is apparently armed with this knowledge that our model fathers-in-law are willing to give so freely to their sons-in-law.
