Kathy D. Patrick is a Houston lawyer who spends her Sundays teaching children about God. The rest of the week, according to one attorney who knows her, she can be “as frightening as a pit bull on steroids.” That’s bad news for issuers of mortgage-backed securities like Bank of America Corp. Patrick represents bond investors including the Federal Reserve Bank of New York and BlackRock Inc. who are seeking to force the bank to buy back bad home loans, claiming the debt failed to match contractual promises about its quality. Her law firm, Gibbs & Bruns LLP, is a 30-lawyer outfit that says it specializes in “bet the company” litigation. This month, it reached a settlement with JPMorgan Chase & Co. and Bank of Montreal stemming from an alleged fraud at a Canadian gold company. Earlier this year, Goldman Sachs Group Inc. and UBS AG settled with the firm over the sale of $550 million in mortgage-backed securities. Patrick reached that settlement on behalf of her clients just two months after filing suit.